How to encourage to migrate to RH 6 ?

We have several RH servers with many, many RH 5 servers. There many types of applications running on them
like web servers, databases, in-house apps, external, commercial apps (imagine anything you can ...).
Applications owners/admins are not really eager to migrate to RH 6 since they value RH 5 stability and can't see any advantage of migration to 6.
Can you recommend anything I could use to "help" them decide to migrate (of course I don't want them to force to do that) ?
All the changes between RH 5 and 6 are known for me (and there are a lot of white papers about it) but any list what might be
encouraging for applications administrators (not Linux administrators) ?
One is RH Software Collections.
Anything else ?