For those not following the Incredible Hulk current storyline, I highly recommend you begin reading it. As most of us all know, Bruce Banner is no longer able to transform himself into the Hulk. In recent times, a bunch of bad guys, lead by The Leader plan on drawing knowledge from the eight smartest people in the world - Reed, Doom, Pym, Hank etc.
Banner has been working with Red Hulk to stop them. I wont exactly spoil the whole story here, but just to stir your curiosity, we now have, Red Hulk, Red She Hulk, She Hulk, Savage She Hulk, Skaar, A-Bomb, and Samson. All of whom make the story really good.
Anyway, Spider-Man has been playing quite a substantial role in this story as Banner recruits him, among others to help stop the bad guys. Somewhere along the line, Banner, one of the eight smartest guys, gets captured by the Leader.
Moral of the story, the plan fails, and everyone get turned into a Hulk. This includes Thor, Capt America, Deadpool, Spider-Man, Ms Marvel, the Fantastic Four, Wolverine and others - thus explaining the covers below.
Below is a little description of Spider-Man Hulk from Hulked Out Heroes # 1