2:38pm: Wallace's contract is non-guaranteed, Jared Zwerling of ESPNNewYork.com confirms (via Twitter). You can view the full list of Knicks on non-guaranteed deals right here.
12:24pm: The Knicks have officially signed Rasheed Wallace, the team announced today in a press release. The deal is expected to be for one year at the minimum salary, though it's not clear whether or not it's fully guaranteed. Marc Berman of the New York Post reported earlier today that the deal likely won't be guaranteed unless Wallace makes the team.
Although Wallace has flirted with the idea of a comeback over the last two years, he hasn't played in an NBA game since the 2010 playoffs, when he and the Celtics were defeated by the Lakers in the Finals. The veteran big man has played in nearly 1100 games since entering the league in 1995, but it'll be interesting to see if he's still able to contribute much at age 38, after two years out of the NBA.
With Wallace's signing, the Knicks now have 20 players in training camp. Of the other 19 Knicks contracts, 13 are believed to be fully guaranteed, so there should be a couple roster spots available for the remaining camp participants. If Wallace shows he's healthy and in shape, I imagine he'll earn one of those last two spots.
Jared Zwerling of ESPNNewYork.com first reported that Wallace had taken a physical with the Knicks last week, while Berman reported that Wallace had informed the Knicks he'd sign with them.