That's not to be confused with QB Eagles, for all you Tecmo fans out there.
Yes, the New England Patriots signed Vinny Testaverde as (so I have read and heard) as their "3rd" quarterback.
I don't think they expect him to play. Ever. Even if Tom Brady gets injured. Maybe if Brady and Matt Cassel get hurt. Nor has he been brought in to "light a fire" under Brady. He's a sounding board, almost a coach.
Since Brady has been quarterback, and pretty much while anyone is quarterback anywhere in the league, there's another quarterback on the sideline, usually someone with experience, to talk to the guy on the field, keep things organized, bounce things off, etc. New England hasn't had that this year, and it may be one reason why Brady has "stuggled" and has had all kinds of "body language" and "mental health" issues.
While I'm sure the Pats didn't break the bank on Testeverde, that enormous cache of cash New England had lying around (that everyone complained they weren't spending on Deion Branch and others) is surely dwindling.