Having been killed off in the climactic battle with Wolverine and Sabretooth, it turns out that Wade Wilson's healing factor is actually stronger than the brothers believed. So while his head was removed, the post-credits sees him open his eyes as a hand picks up the decapitated head.
What It Teased
Well, another appearance by this abomination of a Deadpool. Presumably, if he'd been well received, we might have seen him return in a future Wolverine/X-Men movie.
Origins bombed and was counted as a critical joke, particularly in the way it had presented Deadpool. The idea that the studio added a post-credits sequel sting hinting that we could get MORE of that monstrosity was just ridiculous and added fuel to the abuse.