As far as software, for me, SBSettings is vital. Apple still doesn't have a quick way to access Wifi, brightness, airplane mode and other settings, and until they do, I wouldn't think about running without a jailbreak. I also still prefer Lock Info to Apple's Notification Center.
yes, obviously. 'unlocked' = 'works on any carrier with which the technology (ie GSM/UMTS, works on the right bands) is compatible'. note that since tmobile almost exclusively uses an unsupported-by-Apple band for 3G (1700MHz), you're getting EDGE at best.
I guess not everybody wants all that stuff, but I do. :)
I remember a few months ago, there was a flux thread. A couple of people were lamenting over the fact that it wasn't available on iOS. I even e-mailed Marco over at Instapaper to see if he could implement the feature.
Now that it's available, I'll finally be able to use my iOS devices at night!
That being said, even if I did want untethered jailbreaking right now, I'd be left in the dark, as I am one of (many) people who have both an iPad 2 and iPhone 4S.