Not until summer
We won't see another TM upgrade until at least mid to late summer. After apple had to issue all those store credits for the 4gb iPhone 1g they will think twice before doing upgrades this close together.
I know quite a few people probably jumped on the new TM with the dual-band and apple would hear a huge outcry from that group if they were to upgrade within a matter of one or two months unless they offered free upgrade, which I do not see happening. So just wait, they will come eventually, but not until at least July.