The most exciting addition is Ryan Lavarnway. The young righty was impressive in his first trip to the majors, reaching base more than 40% of the time. While he didn't show off his power in his limited time, its presence isn't really in question.
Kyle Weiland has had a more difficult time adjusting to the majors, running into some consistency issues on the mound. It's possible a trip to the bullpen will help the young righty figure things out.
As for Nate Spears, this move seems to be more about defensive depth than anything. While the infielder had a surprising 2010, hitting 20 homers in Double-A Portland, he hasn't sustained that offensive performance through to 2011. Don't expect too much from Spears aside from possibly the occasional defensive replacement in late innings on the left-side of the infield.