If your developers use Visual Studio Pro or better, they can chose to install SQL Server Developer edition as part of the VS install. As mentioned, SQL Server Developer edition is feature-identical to SQL Server Enterprise. You may also note that SQL Server 2012 introduces 'LocalDB' for offine development - more about that here.
For working with any developer edition of SQL Server, there are a couple of options:
Use the (minimal) tools included for connecting to databases
inside of VS
Download and install SQL Server Data tools from here - I blogged about what you can do with SSDT here. You can run SSDT from within VS or stand-alone.
- Download and install SQL Server Management studio - here
- Download and install SQL Server Express w/Advanced Services from here -
which includes a version of SQL Server Management Studio
Here's a blog that compare SQL Server tools for SQL Server 2008.