Major factors
1. The daily RSI has almost hit 30. This has happened very rarely in the past, and it always leads to a move up!
2. Depth actually looks pretty healthy right now, contrary to statements by people like Edward.
3. We just hit a major support level -- the 3.8-4.2 range.
Smaller factors
1. Size of this correction is roughly 50%, important Fibonacci retracement level. (7.2->3.88)
2. Looks exactly like Spring '11.
3. Everyone's bearish on the forums
4. The big sellers have probably run out of BTC.
5. MACD hit its own long-term support.