There's never been a cut and paste feature on a 100% touch based device before. Apple had only one chance to get it right. (edit - maybe I'm wrong here, maybe that Sprint abomination or the Storm has it, but they'll be relegated to the dustbins of history and are not platforms the way the iPhone is a platform)
There are a lot of simple interactions on a touch device - tap to select, pinch to zoom. But a complex interaction like select, cut, paste, copy - there's an infinite number of ways you could implement this, and many of them are really bad.
Apple doesn't want to try to introduce a new interaction into the touch lexicon, then decide later it was totally inadequate and replace it and cause user confusion.
Think back to all the would-be designers you've heard saying how easy it would be to implement and then gave their own ideas for a design. Some of them were pretty good. Some of them were downright awful. I think what Apple finally came up with here is pretty fantastic.
It comes off as something so easy to use my mom could do it, and she still struggles with the desktop standard of cut and paste - mouse, ctrl-x, ctrl-c, etc.
I'm sure we'll see copycat devices copy this interaction verbatim, just like pinch zoom and other things are permanent fixtures of the touch interface lexicon. That's how good it is.