First of all, the Jumpdrive trio is simply a card reader. It has no internal memory itself. You can put any size SD/MMC/Memory Stick into it and use it like any other thumb drive type device.
Second, from what I have learned reading on these forums, and others, you are correct with your guess that the T3 will not work with a 2G SD card. As far as I know the upper limitation on the T3 is 1.54G. And there is a company out there that sells cards that size. I can't for the life of me remember who that manufacturer was, but it is out there.
And many people have requested a FAT32 driver for the T3, but I don't see palm doing it, since that platform is, sadly, not produced any more.