Maybe, but the problem is Apple restricts running applications (those that aren't from Apple) as background processes, making it difficult if not impossible to implement something like copy/paste which must be a global service. The file browser is more likely, although Apple hasn't officially implemented a sandboxed general storage area yes AFAIK (but signs are they probably will at some point).
Oh yes, what I meant was, with the 2.0 Software, they had one giant feature, and subsequent smaller one's. With the next big update, "Copy and Paste" will be the "App Store," giant feature of the update, not that Copy and Paste would be in the app store itself.
Think about it, OS X updates have a few major features, and many minor one's. The same would be the case with iPhone major point updates. While the App Store took a lot of technical time to build, Copy and Paste will take a lot of theoretical time to implement to make sure it's as user friendly as they'd like.