Matt Maiocco: NFL Trade Period begins March 12 and 1 PM. 

http://www.csnbayarea.com/blog/matt-maiocco/49ers-mailbag-trade-period-begins-march-12
How soon can Alex Smith be traded? (@S49erfan) 
The new league year begins March 12, 1 p.m. (PT), at which point the NFL trade period opens.So the 49ers have a 19-day window to work out a deal with another team for quarterback Alex Smith. If Smith is on the 49ers' roster on April 1, the club must guarantee his $7.5 million base salary. If something is going to happen, it'll likely happen quickly.

What do you think the ‪49ers‬ chances are of trading for Percy Harvin? (@MarquisDotCom) 
My blanket answer for all questions regarding potential trades is "slim."After all, think of all the times the question has come up about 49ers potential trades over the past few years. Yet, there was only one player on the roster last season the 49ers acquired in a trade: Ted Ginn.Good teams treat their draft picks like gold. Teams that want to win consistently generally do not hand out big contracts to attract players from other teams. Yes, Harvin's contract for 2013 makes him affordable, but he would want a lucrative extension from any team that acquires him.

H‬as the NFL had ANY official communication regarding the obvious one-sided non-calls against the Niners in the sb? (@john_49_) 
The NFL does not comment on officiating issues that involve judgment calls. However, Dean Blandino, the new NFL vice president of officiating, had this to say to Newsday's Bob Glauberabout the controversial fourth-down pass to Michael Crabtree that did not draw a penalty flag for defensive pass interference against Baltimore cornerback Jimmy Smith:"When you watch it at full speed, to me, it was a good non-call. I think the first thing you have to understand is that once the ball is in the air, you can't have defensive holding or illegal contact. Now you have to see if the contact raised to the level of pass interference."With pass interference, you have to materially affect the receiver's ability to catch the pass. Yes, there's hand-fighting, but Crabtree also has his hand on (Smith's) helmet. The pass was catchable, but the contact did not materially restrict Crabtree's ability to catch the pass. He was jockeying for position and using his hands as well."