Well, it certainly took a long time, but it looks as though the Nate Robinson deal has finally been completed, according to The Boston Globe:
The Celtics have acquired Nate Robinson and Marcus Landry from the New York Knicks in exchange for Eddie House, Bill Walker and J.R. Giddens, who were thrown into the deal to match salaries.
The Celtics are waiting for NBA approval and the deal may not be announced until later this afternoon.
So who exactly is Marcus Landry? He's a 6'7 rookie out of Wisconsin. Beyond that, I really can't tell you a whole lot. You've probably heard of his brother, Carl Landry, who was actually traded to the Sacramento Kings earlier today. Here are some links to help you get acquainted:
ESPN.com - Marcus Landry (College Profile)
ESPN.com - Marcus Landry (NBA Profile)
Jessica Camerato of WEEI also has a short profile on Landry.