The first chart below is light sweet crude oil futures. Note two things: 1) Oil has broken out of a long consolidation pattern (light blue lines) and closed above it on a weekly chart. 2) Oil has now retraced 61.8% of the down move in 2008. All in all, that's bullish.
The second chart is the USO ETF, which might be the way to trade oil On a daily close above $40 I will be looking to go long the USO.