I consider myself both first and second wave user, since I got my tracking number today and will have in hand tomorrow. First wave, I'll run in parallel with my E71 by just adding a 2nd T-Mo SIM (I'm on Even More Plus, so no contract since I roll my own phones). There are too many missing features that are critical to me in the current state (e.g., real Mail For Exchange support as on e71 is a must have for me) and I really want my primary phone to be bulletproof in it's role as a phone.

Second wave, as I am hoping Nokia doesn't abandon this phone like they abandon all their other phones and continues to release updated firmware to address the key issues to bring it a bit closer to parity with Symbian with respect to phone features. So I can eventually use the N900 as my primary phone and leave the e71 behind.