The interface would be sort of a challenge, though, as the web browser hides a lot of events. (The main issue would be to define an interface to allow selections, since iphone safari merges buttondown and buttonup). Would have to do something lame like touch the start of the selection, then press a "extend selection" button and touch the end of the selection. Very 1980's.
Since the rumor is that os-wide copy/paste is supposedly coming when the file browser comes, presumably they'll either unmerge the events or add some sort of "select" gesture in the future.