T-Mobile is catching up, and I think this is a smart move for them. They have seen the problems AT&T has had with the iPhone and are already deploying 21 Mbps HSPA+ in preparation for the coming onslaught of smart phone users, before users notice.
I think its less for smartphones (doubtful that we'll see too many 21Mbps phones, let alone 14.4Mbps). Datacards are where the 'big' difference will be.
Since T-Mobile's currentl deployment is relatively small, there's no reason to not deploy HSPA+ 21Mbps.
