Lots of fun with the Sidekick. It seems to work now.
I had to power cycle it to get the network to work the first time.
GSM/GPRS coverage is spotty around Palo Alto; I can move 10 feet and get full signal vs. no signal. Plus, even when there is a strong signal, the data connectivity shows disconnected. Either T-Mobile and Cingular are fighting for connectivity (sometimes the "Phone" screen shows one, sometimes the other), or there's some random firmware bug. In any case, I hope they get it worked out.
But when (where?) it works, it's great.
I gave Becky my T900.