While we knew that copy and paste is coming to Windows Phone in the first half of 2011, no other specific time frame was given although there is a rumor of a January update, which now seems to be accurate. Arpan Shah, a Director at Microsoft who leads Product Management for Microsoft Project, mentioned in passing about when we can expect that update:

Critics have commented on the lack of specific features like copy & paste and lack of 100s of thousands of applications. And while both are true, copy & paste will be available as an update in a matter of weeks (early 2011) and as for applications, it’s just a matter of time.

While not written and stone and we're sure Microsoft would not want to publicly commit to such a timetable, we believe that this is probably quite accurate. If so, we can finally stop hearing about the lack of said feature as a knock against an otherwise fantastic v1.0 release. The rest of that January update is rumored to bring task-manager/hub mutlti-tasking, turn-by-turn directions, clipboard and Skydrive/OWA support.

Source: Arpan Shah's Blog