$13,560 is the limit for 2008 (and should increase considerably (due to larger CPI) for 2009). That is the limit you can earn before giving up a $1 for every $2 earned above that amount if you are under the full retirement age (66 and up). Your K-1 income would count towards that limit. Having said that you should contact the SSA (or search their Web site for solid information).
BTW welcome as I see this is your first post here.
Vietnam Veteran, CW4 USA, Retired 1979