650, 680, and 700p, to be exact). Into the password-protected ether, as far as we can tell; it appears that carriers are involved in the action, since it currently only works for AT&T, Sprint, and Verizon customers. The software and service are free (though an unlimited data plan is, obviously, highly recommended) and can be kicked off from anywhere you have a signal. It can also be set to automatically kick off on a schedule, and it only chews up 2MB of storage space on your beloved Treo. As with any beta, be wary -- but at least it's free, right?
[Via Wirelessinfo, thanks Emily]