Usually Cingular doesn't lock handsets, you're right.
I don't know what their policy on BigDevices such as Treo's and bberry's is.
I do know that I think I'll really prefer a 7290 to a 7230 or 7100t.
I'm using a 7230 now and will get a 7100t this week.
Knowing me, I'll end up getting a 7290 as soon as I can. Meanwhile, T-Mobile is selling "Blackberry Jr's" at record pace. It's getting hard to get GPRS up here in Providence, RI with all the kids on their SideKicks!