I have T-Mobile, but no Blackberry. The whole deal with Port 80 was that before not too long ago (late November I think), those who paid for the $4.99 t-zones extra received basically unlimited access to the internet. It's basically something that T-Mobile never really paid too much attention to. But, once they figured out they were stupid for giving out something so cheap, they took away the unlimited access, and stuck it on the $19.99 t-zones plan. The $4.99 plan is now limited to basic wap browsing and the like. Lots of people got pretty upset because they basically had been downgraded overnight.
So, point being, if you had the $4.99 plan and unlimited internet before the Port 80 closure, then yes, you'd be getting screwed. But if you're just now coming into T-Mobile, you're not getting screwed at all. From what I can tell, depending on how much of the internet you will use, T-Mobile now has a comparable rate to other companies (<-- don't hold me to that though). Can't blame T-Mo for wanting to make money where there's opportunity. I'm sure that for every 3 that canceled, 1 upgraded to the $19.99 plan, which would not lose T-Mo any money currently.