The opening begins with 1.e4 c5 2.b4. If memory serves, Alekhine and Keres used to play it occasionally, but delayed it by playing 1.e4 c5 2.Nf3 followed by 3.b4 which seems to me is the better way.
After Black captures 2...cxb4, the usual continuation is 3.a3 bxa3 (3...d5! is more recently considered superior) and now the main line is 4.Nxa3, though 4.Bxa3 and 4.d4 are also seen. White gets quick development and a central advantage, but it is not generally considered one of White's better choices against the Sicilian and it is virtually never seen at the professional level.
After Black's 2...cxb4, another popular third move alternative for White is 3.d4. It is also possible to prepare the gambit by playing 2.a3 followed by 3.b4. One thing to remember if you play this gambit is that the b-Pawn is lost…there is no chance of getting it back. The short version is than if you play the Wing Gambit, you have lost time, material and positional advantage which is why it’s rarely played at the master level.
If Black accepts the Pawn then White has a lot of possible ways to continue: a3, d4, c4 or even c3. Because there’s not a lot of theory on the opening and few Black players will know much, if anything, about it, expect games to go every direction! There are some books on this gambit, but I wouldn’t bother buying them because of this reason.
In the following game I played a novelty on move 5. It was a mouse slip and I ended up with a miserable position. At first I thought I would just follow it up with d4 getting a big center. I did eventually get in d4...at move 46. As it was, the game was pretty messy and looking it over with Houdini 2, Stockfish 4 and Komodo 5 showed it to be not so well played by either of us, but it’s worth looking at because of all the tactics, both seen and unseen.