I've heard a surprisingly large amount of people tell me that it's essential that they can copy and paste text* on a phone. Personally I hardly ever used this feature when I was using a phone which had it though.
I've pointed out to a few people that it's possible to implement the cutting, copying and pasting of text within an application quite easily. (It actually only take a handful of lines of code.) But no-one (AFAIK) has taken the initiative to do this. Before now...
The issue isn't really being able to cut and paste text though. What people really want is a way to easily share data between applications. When people say "cut and paste" they, typcially, mean they want to take (copy) some data (text) from one application and then use (paste) it in another application.
As native functionality, this isn't currently possible.
However this will be coming in an remote update early next year.
So if we want copy and paste in our apps we have to either wait or try and do it ourselves.
Surprisingly, the sandboxed nature of 3rd party applications on the phone has lead many (most?) to assume that this isn't possible.
I beg to differ!
Take a lok at this video of 3 apps I wrote. 2 accept the entry of text and support methods of multiple word selection (also not currently available natively) and cutting, copying and pasting text. The third app just shows what is in the "Shared Clipboard". Yes. These apps all have access to the same clipboard. And, no, this isn't done by sending the data to a remote web server or anything like that. It's also not using anything not publically available and only uses public, authorized API methods.
To try and prove that this is really possible I've submitted Scratch Pad to the marketplace. When it's accepted you can try it for yourself. Plus acceptance will show it's not using anything it shouldn't (or you couldn't) and that it doesn't require a data connection.
With native support for cut and paste coming in early 2011 (most people are assuming in January) I'm not planning on sharing the clipboard code as there is a small side effect to using it that it's probably best not to burden users with. But, I assume that you're smart enough to work out how I did this if you really wanted to. ;)
* It's always text that people want to copy and paste. I haven't, yet, heard anyone give a case for wanting this for any other data type on a phone.