I have a Treo 650, and can second the complaints about instability, although it's only crashed once in the middle of a call.

(as an aside, does anyone else who lived through the Mac System 7.5/Windows 3.1 days have a very strong feeling of deja vu when using mobile devices? I mean, do I really have to live through this crap again just so I can have a decent digital calendar on my phone?)

And while Chattermail does indeed do the IMAP instant-ping thing, that's actually the reason I decided not to register it, and regretfully uninstalled it after the trial ran out.

When my pocket goes "buzz" the instant someone else has decided they want my attention, that's shifting the balance of power in the wrong direction. Snapper mail is more expensive (much!) and I don't like the way it works quite as much as I liked Chatter, but I can specify set intervals for it to check my email. And that shifts control of my attention into my hands.

(Korean missile silo, blah blah blah.)

I can always decide to check mail more often than once every half hour if I have discretionary time, but if something is that earth-shatteringly important that it can't wait the average 15 minutes it'll take me to get it, there's this wonderful feature of phones that you might not have heard of, where they make a noise that indicates that someone wants to talk to you? And then you can talk to me. Like, with your voice. And tell me that the building is on fire.

Not to bash the blackberry. I'm just not able to deal with the interruptions as well as I should. Kudos to anyone who can.