Know what would be really handy? To include all your friends’ and acquaintances’ contact info — including Twitter handles, Facebook profiles, phone numbers, email addresses, RSS feeds, [foreign: und so weiter] in some global address book (like the nice Gmail contacts list, which you can sync with a mobile device, and which I sync quite happily with the iPhone), then gather together all those items and make them on the device. Quite often a conversation starts via text message, moves over to email, maybe ends up in a voice chat, turns into a blog post, etc. Wouldn’t it be nice if the device could record your voice chats, or at least transcribe them?
Barring that, just being able to search text messages at the same time as you search emails would be a big win. Didn’t BitPim do this?