I'm using SleepCycle until my WakeMate arrives. It's very good, but my problem is that I sleep with my girlfriend, and the iPhone seems to record both our movements. I tried last it last night without my gf sleeping (she's on a trip) and I found the graph to be quite different.

I imagine having WakeMate's wristband will negate anyone else's movements on the same bed, and record just your own.