There hasn't been any changes to schedules behavior in Unity 4.x - There is work being done along these lines for future releases but nothing on the short term radar at this point. Down the road there will be significant changes to how schedules (or "Schedule sets" as they'll be called) are handled and how greetings are dealt with (there will be designated holiday greetings and multiple languages will be handled by one set of greetings). It's in the pipe line... I can't give out anything approaching a date for anything like this, though - sorry.
You can do holiday greetings in 3.x/4.x currently but you have to chain a couple handlers together to do it - you can get details on this in the "Audio text applications in Unity" paper on the Documents page of www.CiscoUnityTools.com if you want.
