I noticed two new web applications doing something interesting: serving their iPhone interface to everyone. Muxtape uses an iPhone-style interface for its playlists, which works great on an iPhone but for the fact that the MP3s don’t play (at least, for me — doesn’t the iPod app load MP3s from MobileSafari? I guess not). Instapaper takes this further, and makes a web interface that you wouldn’t know works great on an iPhone unless you happened to try it. (Their FAQ even addresses the question since it’s not that obvious.)
The result is that everyone who tries these apps gets a simple, clean UI. Talk about limitations producing great effects.