Next month is when the Push Notification will be released to developers and in September it will be released to everyone, so you'll be able to see if you have new IMs without the app actually running. I'm guessing you'll see chat clients out next month but they'll be updated when the Push Notification comes out. Sucks they didn't think of this in March when the first SDK came out.
Originally Posted by xintelinsanex
As for Hotmail on the iPhone, I HIGHLY doubt it. You have to pay for Hotmail's service (not too surprising though coming from Microsuck) to access it through Outlook or Mail.app. Just another reason to use Gmail.