Okay, I am a self-taught piano player, so I was in exactly the situation you are in now.
My main suggestion to you would be to think of some guitar songs you can play that are fairly simple, and then transfer them over to the guitar. I learned to play loads of songs on the piano that way.
Okay, easy songs for the piano (most of which I will have learned through guitar) include:
Coldplay - The Scientist (1. Love them or hate them, this is a crowd pleaser, as is Trouble. 2. Don't bother trying to figure it out on the guitar from the recording, because the piano they use is out of tune. The chords are D minor, Bb, F(sus4) and C (which a little bit in between the C that you can figure out easily, it's just the whites notes between your root and your fifth))
Nick Cave - 15ft Of Pure White Snow
As I Sat Sadly By Her Side (these two songs are based around the same three chords, and their little piano are both really easy, but sound very cool and competent when you play them)
Robbie Williams - Feel (if you're American you may not know him)
Wilco - Poor Places, At Least That's What You Said, Ashes Of American Flags
That's all I can think of right now. If your guitar playing ability isn't quite enough to match this, or there was any of this you didn't understand, don't hesitate to ask.