there's quite a few coming out:
DX2 - Q2, dual core, but no LTE
DInc2 - Q2, dual core, but no LTE (i think)
D3 - Q2/Q3, dual core, pkb, 4" screen, but no LTE
Galaxy S2 - unsure when coming out (probly Q3/Q4) - it's very close to, if not the best phone on the horizon
Targa/Bionic - Q3, dual core, LTE - imo, very comparable to the GS2.
Atrix - Q4, dual core, LTE, webtop app
dual core will quickly leave single core obsolete. faster processing speeds, less heat, less battery consumption (in theory), etc, etc... imo, by the end of the year, most everyone who bought a single core device (TB, Charge, etc) will be lamenting their purchase and looking for a way to upgrade early...