Gaslight Anthem have apparently signed to SideOneDummy. Though no official announcement has been made, the band is now listed on the label's website.
The band released Sink or Swim in 2007 to considerable acclaim and will soon be issuing Senor And The Queen via Sabot. The band is currently at work on their sophomore full–length to be released on Side One Records in late Summer or early Fall 2008.
Update: Here is a direct link to the band's profile page on SideOneDummy.