There is no way that the PPA could be a 501(c)(3) with its activities. Lobbying efforts alone would pretty much finish that possibility. They are a 501(c)(4) membership organization.
I found their 2005 Form 990 from their website here:
http://www.pokerplayersalliance.org/...5Public990.pdf
It should be noted that their 2006 form was probably extended and would be due on the 15th of this month.