According to an NME report, Blink 182 have already begun working on the follow up to Neighborhoods in 2011. Co-vocalist Mark Hoppus said this to the British magazine:

Right now, I'm writing songs and Tom is doing other stuff. Basically, we've been on a break since last summer's US tour. I'm sure these will all be Blink songs at the moment. I don't have any plans to write songs with anybody else right now. If I do, it'll be a collaboration or a one-off thing, but everything I'm writing right now is for Blink-182. [As for the sound], i's really too early to tell. At the moment all I've got is a bunch of chord progressions and ideas. It's more me playing my guitar and coming up with little ideas and melodies. By the time it goes to Tom and Travis and we work on it as a band, who knows what it will sound like.

Check out the video interview here.