I ended up getting an iPhone after all. I got my fianc?e one for Christmas and after borrowing it a few times, realized that the keyboard wasn't a problem once I got used to it, and the App Store is a real draw. Add a family-talk plan and a 20% rebate through my school, and I'm paying the exact same for two iPhones that I was for one BB Pearl on T-mo. I also eventually persuaded T-mo to let me out of my contract early, since I hadn't been able to use the Internet reliably for months and no one could fix it. Thanks to everyone who helped my decide!
As for dual-sim on smartphones, I haven't heard of any. The only phones I know can do two numbers are some Motorola models that Sprint sells, but I don't know if any are smartphones, and they definitely don't support SIM cards since it's a CDMA network.