T-Mobile just announced their upcoming Valentine's Day sale: all smartphones will be free on a new 2-year agreement, upgrade, or the addition of a new line from February 11-12. This includes all two of T-Mobile's available HSPA+ devices: the G2 and myTouch 4G. Why this Valentine's day sale doesn't actually take place on Valentine's day is somewhat obvious: a slew of new Android handsets will probably be announced that day at the Mobile World Congress in Barcelona.
If you're looking to get a solid Android handset (or "4G" subject to your definition) on the cheap, T-Mobile's deal is pretty attractive. Be wary, though - with devices like the Samsung Galaxy S 4G and likely others to be revealed at MWC, you may end up kicking yourself within days of your purchase.