This script will provide you with detailed information on SQL Server Agent Jobs and their schedules. This doesn't include any scheduled task that may exist in Scheduled Tasks for Windows.
USE msdb
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SELECT dbo.sysjobs.Name AS 'Job Name',
'Job Enabled' = CASE dbo.sysjobs.Enabled
WHEN 1 THEN 'Yes'
WHEN 0 THEN 'No'
END,
'Frequency' = CASE dbo.sysschedules.freq_type
WHEN 1 THEN 'Once'
WHEN 4 THEN 'Daily'
WHEN 8 THEN 'Weekly'
WHEN 16 THEN 'Monthly'
WHEN 32 THEN 'Monthly relative'
WHEN 64 THEN 'When SQLServer Agent starts'
END,
'Start Date' = CASE next_run_date
WHEN 0 THEN null
ELSE
substring(convert(varchar(15),next_run_date),1,4) + '/' +
substring(convert(varchar(15),next_run_date),5,2) + '/' +
substring(convert(varchar(15),next_run_date),7,2)
END,
'Start Time' = CASE len(next_run_time)
WHEN 1 THEN cast('00:00:0' + right(next_run_time,2) as char(8))
WHEN 2 THEN cast('00:00:' + right(next_run_time,2) as char(8))
WHEN 3 THEN cast('00:0'
+ Left(right(next_run_time,3),1)
+':' + right(next_run_time,2) as char (8))
WHEN 4 THEN cast('00:'
+ Left(right(next_run_time,4),2)
+':' + right(next_run_time,2) as char (8))
WHEN 5 THEN cast('0'
+ Left(right(next_run_time,5),1)
+':' + Left(right(next_run_time,4),2)
+':' + right(next_run_time,2) as char (8))
WHEN 6 THEN cast(Left(right(next_run_time,6),2)
+':' + Left(right(next_run_time,4),2)
+':' + right(next_run_time,2) as char (8))
END,
-- active_start_time as 'Start Time',
CASE len(run_duration)
WHEN 1 THEN cast('00:00:0'
+ cast(run_duration as char) as char (8))
WHEN 2 THEN cast('00:00:'
+ cast(run_duration as char) as char (8))
WHEN 3 THEN cast('00:0'
+ Left(right(run_duration,3),1)
+':' + right(run_duration,2) as char (8))
WHEN 4 THEN cast('00:'
+ Left(right(run_duration,4),2)
+':' + right(run_duration,2) as char (8))
WHEN 5 THEN cast('0'
+ Left(right(run_duration,5),1)
+':' + Left(right(run_duration,4),2)
+':' + right(run_duration,2) as char (8))
WHEN 6 THEN cast(Left(right(run_duration,6),2)
+':' + Left(right(run_duration,4),2)
+':' + right(run_duration,2) as char (8))
END as 'Max Duration',
CASE(dbo.sysschedules.freq_subday_interval)
WHEN 0 THEN 'Once'
ELSE cast('Every '
+ right(dbo.sysschedules.freq_subday_interval,2)
+ ' '
+ CASE(dbo.sysschedules.freq_subday_type)
WHEN 1 THEN 'Once'
WHEN 4 THEN 'Minutes'
WHEN 8 THEN 'Hours'
END as char(16))
END as 'Subday Frequency'
FROM dbo.sysjobs
LEFT OUTER JOIN dbo.sysjobschedules
ON dbo.sysjobs.job_id = dbo.sysjobschedules.job_id
INNER JOIN dbo.sysschedules ON dbo.sysjobschedules.schedule_id = dbo.sysschedules.schedule_id
LEFT OUTER JOIN (SELECT job_id, max(run_duration) AS run_duration
FROM dbo.sysjobhistory
GROUP BY job_id) Q1
ON dbo.sysjobs.job_id = Q1.job_id
WHERE Next_run_time = 0
UNION
SELECT dbo.sysjobs.Name AS 'Job Name',
'Job Enabled' = CASE dbo.sysjobs.Enabled
WHEN 1 THEN 'Yes'
WHEN 0 THEN 'No'
END,
'Frequency' = CASE dbo.sysschedules.freq_type
WHEN 1 THEN 'Once'
WHEN 4 THEN 'Daily'
WHEN 8 THEN 'Weekly'
WHEN 16 THEN 'Monthly'
WHEN 32 THEN 'Monthly relative'
WHEN 64 THEN 'When SQLServer Agent starts'
END,
'Start Date' = CASE next_run_date
WHEN 0 THEN null
ELSE
substring(convert(varchar(15),next_run_date),1,4) + '/' +
substring(convert(varchar(15),next_run_date),5,2) + '/' +
substring(convert(varchar(15),next_run_date),7,2)
END,
'Start Time' = CASE len(next_run_time)
WHEN 1 THEN cast('00:00:0' + right(next_run_time,2) as char(8))
WHEN 2 THEN cast('00:00:' + right(next_run_time,2) as char(8))
WHEN 3 THEN cast('00:0'
+ Left(right(next_run_time,3),1)
+':' + right(next_run_time,2) as char (8))
WHEN 4 THEN cast('00:'
+ Left(right(next_run_time,4),2)
+':' + right(next_run_time,2) as char (8))
WHEN 5 THEN cast('0' + Left(right(next_run_time,5),1)
+':' + Left(right(next_run_time,4),2)
+':' + right(next_run_time,2) as char (8))
WHEN 6 THEN cast(Left(right(next_run_time,6),2)
+':' + Left(right(next_run_time,4),2)
+':' + right(next_run_time,2) as char (8))
END,
-- next_run_time as 'Start Time',
CASE len(run_duration)
WHEN 1 THEN cast('00:00:0'
+ cast(run_duration as char) as char (8))
WHEN 2 THEN cast('00:00:'
+ cast(run_duration as char) as char (8))
WHEN 3 THEN cast('00:0'
+ Left(right(run_duration,3),1)
+':' + right(run_duration,2) as char (8))
WHEN 4 THEN cast('00:'
+ Left(right(run_duration,4),2)
+':' + right(run_duration,2) as char (8))
WHEN 5 THEN cast('0'
+ Left(right(run_duration,5),1)
+':' + Left(right(run_duration,4),2)
+':' + right(run_duration,2) as char (8))
WHEN 6 THEN cast(Left(right(run_duration,6),2)
+':' + Left(right(run_duration,4),2)
+':' + right(run_duration,2) as char (8))
END as 'Max Duration',
CASE(dbo.sysschedules.freq_subday_interval)
WHEN 0 THEN 'Once'
ELSE cast('Every '
+ right(dbo.sysschedules.freq_subday_interval,2)
+ ' '
+ CASE(dbo.sysschedules.freq_subday_type)
WHEN 1 THEN 'Once'
WHEN 4 THEN 'Minutes'
WHEN 8 THEN 'Hours'
END as char(16))
END as 'Subday Frequency'
FROM dbo.sysjobs
LEFT OUTER JOIN dbo.sysjobschedules ON dbo.sysjobs.job_id = dbo.sysjobschedules.job_id
INNER JOIN dbo.sysschedules ON dbo.sysjobschedules.schedule_id = dbo.sysschedules.schedule_id
LEFT OUTER JOIN (SELECT job_id, max(run_duration) AS run_duration
FROM dbo.sysjobhistory
GROUP BY job_id) Q1
ON dbo.sysjobs.job_id = Q1.job_id
WHERE Next_run_time <> 0
ORDER BY [Start Date],[Start Time]

Update 11/4/2013
Here is another script that associates plans with their associated jobs
SELECT
s.name as [PlanName],
spl.start_time AS [StartTime],
spl.end_time AS [EndTime],
spl.succeeded AS [Succeeded],
sysjobs.name as [JobName],
'Frequency' = CASE sysschedules.freq_type
WHEN 1 THEN 'Once'
WHEN 4 THEN 'Daily'
WHEN 8 THEN 'Weekly'
WHEN 16 THEN 'Monthly'
WHEN 32 THEN 'Monthly relative'
WHEN 64 THEN 'When SQLServer Agent starts'
END,
'Start Date' = CASE next_run_date
WHEN 0 THEN null
ELSE
substring(convert(varchar(15),next_run_date),1,4) + '/' +
substring(convert(varchar(15),next_run_date),5,2) + '/' +
substring(convert(varchar(15),next_run_date),7,2)
END,
'Start Time' = CASE len(next_run_time)
WHEN 1 THEN cast('00:00:0' + right(next_run_time,2) as char(8))
WHEN 2 THEN cast('00:00:' + right(next_run_time,2) as char(8))
WHEN 3 THEN cast('00:0'
+ Left(right(next_run_time,3),1)
+':' + right(next_run_time,2) as char (8))
WHEN 4 THEN cast('00:'
+ Left(right(next_run_time,4),2)
+':' + right(next_run_time,2) as char (8))
WHEN 5 THEN cast('0'
+ Left(right(next_run_time,5),1)
+':' + Left(right(next_run_time,4),2)
+':' + right(next_run_time,2) as char (8))
WHEN 6 THEN cast(Left(right(next_run_time,6),2)
+':' + Left(right(next_run_time,4),2)
+':' + right(next_run_time,2) as char (8))
END
FROM msdb.dbo.sysmaintplan_plans AS s
INNER JOIN msdb.dbo.sysmaintplan_subplans AS sp ON sp.plan_id=s.id
LEFT OUTER JOIN msdb.dbo.sysmaintplan_log AS spl ON spl.subplan_id=sp.subplan_id
INNER JOIN msdb.dbo.sysjobs sysjobs on sysjobs.job_id = sp.job_id
LEFT OUTER JOIN msdb.dbo.sysjobschedules sysjobschedules ON sysjobs.job_id = sysjobschedules.job_id
INNER JOIN msdb.dbo.sysschedules sysschedules ON sysjobschedules.schedule_id = sysschedules.schedule_id