Where the heck are people getting that Blaziken is faster? Blaziken has base 80 spd while Infernape has base 108 spd. >_>
They're both huge glass cannons that can learn attacks that are supereffective against the other (brave bird and earthquake as mentioned above). Infernape has a huge advantage in speed though, which gives him the edge. :P
If they both are without items, and have adamant natures and EV spreads suited for physical sweepers, Infernape will most likely win. Sorry Blaziken fanboys, but it is truth. =/