I know it's possible to generate a full rman backup in a 10.2g database, move it to another server containing 11g, restore it there and finally do an upgrade.
Since I have to do this to a large database and there are several things involved (apps, servers, network, etc), it could take me a few days and not only one night.
Could I make a full rman backup in 10.2g, restore it in 11g, upgrade, and in the next days go making incremental rman backups in 10g and restoring it in 11g, until we decide to shutdown 10g and use 11g in production. Something like a standby database, but in this case current database would be 10g and standby database would be 11g.