As I wrote yesterday, this wasn't a move the Patriots needed to make, but it was obviously one they were considering. Once the Redskins released him, meaning that the Patriots wouldn't have to part with any draft picks, the Pats clearly felt that it was time for yet another reunion of their 2007 wide receiver corps.
Gaffney joins an extremely crowded wide receiver corps.
The only "true" WR whose spot on the roster is absolutely secure is Brandon Lloyd, who signed a three-year deal this offseason. Slot receiver extraordinaire Wes Welker has yet to sign his franchise tag, so there's at least a chance he won't play this season, but that seems relatively remote.
The Patriots also have a number of wide receivers who are signed only through the end of this season. They brought in former Colts slot receiver Anthony Gonzalez on a one-year flyer, and also brought back former Patriot Donté Stallworth. (The Patriots decided to keep Gaffney over Stallworth in 2008; ironically, they might do so again, four years later.)
Another Patriot stalwart, Deion Branch, whose career was rejuvenated after several stagnant years in Seattle, signed a one-year deal. That deal, unlike Stallworth's includes about $400,000 in guaranteed money, so his spot on the team certainly looks a lot stronger than Stallworth's. It's also stronger than that of Chad Ochocinco, who reduced his 2012 salary by over a million dollars to avoid getting cut. After a disappointing 2011 season, Ochocinco will have to give the Patriots a reason to keep him.
The Patriots also have practice squad members Britt Davis and Tiquan Underwood (who was infamously cut on the eve of Super Bowl XLVI), who at this point look like true underdogs.
Finally, the Patriots have two seventh-round draftees with the initials JE. Julian Edelman, a 2009 pick, is their best punt returner as well as a jack-of-all-trades; he may be listed as a receiver but may not make the squad from that position. Jeremy Ebert, the Patriots' only pick on offense in the 2012 draft, had 11 touchdowns as a senior for Northwestern last year. If he can gain even a reasonable amount of trust from Tom Brady, the Patriots will almost have to keep him, since he would be the only wide receiver both under 30 and under contract for 2013.
At this point, it seems a foregone conclusion that there will be some painful roster cuts at wide receiver this offseason. How it all turns out will be fascinating to watch.