Thanks to tipster Perfectgun, we have this cool little image from the Infamous demo. As you can see, Sly Cooper 4 is pictured in the screen shot. Sly Cooper 4 was already supposed to be out, but got pushed back so Sucker Punch could do Infamous. Here’s a blurb from Wikipedia:
Sly Cooper 4
Sly Cooper 4 (working title) was announced on May 24, 2007 for a speculative 2009 release for the PlayStation 3. The game would have been premiered at E3 2007, and would feature connectivity with the Sly Cooper PSP game for the PlayStation Portable, which will be simultaneously released with the PlayStation 3 version. However, on June 5, 2007, IGN and other sources posted that there has yet to be any confirmation that work on these games exists, and thus this speculation may be incorrect.
Instead, it was announced at E3 2007 that Sucker Punch was working on a PlayStation 3 title called inFamous, a sandbox game based on a futuristic world with more photorealistic graphics, about a superhuman who must make moral choices to save or destroy Empire City. Brian Fleming of Sucker Punch Productions stated in an interview that “We’re broadening ourselves a little bit, taking on some new challenges,” but also noted that “I think it’s extremely likely that you’ll see us return to the ‘Sly Cooper’ franchise at some point in the future.”