http://www.engadget.com/2010/03/16/windows-phone-7-series-wo...
http://www.engadget.com/2010/03/16/windows-phone-7-series-wo...
For most users, I am guessing the most common use case is copying a browser link to an email/IM/SMS, and this can be supported without an actual copy/paste implementation. The hard part of full-blown copy/paste isn't implementing copy/paste storage, it is figuring out the UI for selecting text on a touch screen.
but yes, copy+paste isn't all that necessary, but i can imagine mobile bloggers, among others, needing it from time to time.
btw, don't downvote me for using winmo. i'm not a fanboy, I just get tethering (bluetooth/usb), opera mini (the latest version is great), skyfire (streams flash/sivlerlight). It's a bit slow and the ui isn't great but I use a utily that helps me start apps using keyboard shortcuts and can multi-task (go figure) very easily.