As mentioned in the comments by NFA Brian, the Nationals have signed a couple of pitchers to minor-league contracts.
Most notably, one of those signed was Sam Brown, who was drafted in the 7th round by the Nationals out of high school in 2006 but did not sign. He was drafted again in 2008 by Arizona in the 18th round but did not sign with his drafting team until 2009 by the Texas Rangers. Brown appeared in 31 games and posted a 3.45 ERA (all in relief) for Spokane in the short-season Northwest League that year. He repeated briefly last year before getting promoted to Hickory in the Sally League, but pitched poorly (6.45 ERA, 1.917 WHIP) in 19 games. He released this past January.
Also signed was Scott Mueller, another thrice-drafted pitcher that finally signed with the Baltimore Orioles in 2007. He rose as high as Frederick in 2008, but was released following a dismal 2009 season with Delmarva. He pitched last season in the independent Frontier League, making the All-Star game as a closer for the Traverse City Bums with a 2-0, 2.04 ERA mark and 14 saves in 38 games.
Should they make the cut, Hagerstown would appear to be the most likely destination for the 23-year-old Brown and the 24-year Mueller (both have June birthdays), given their lack of success or experience at High-A (the Frontier League is a middle-tier indy, roughly equivalent to Low-A). It may also be a signal from the front office that there will be fewer pitchers making the leap from the GCL and the New York-Penn League than usual.