I am training for the 2010 NYC Marathon. I had my TX on 11/10/09. So, DUDE...here's my deal.
I did a few road races when I was 10 or 12 years old, but soon after, I lost the ability to run. I always wanted to run, and I dreamed of the day post TX when I could.
Fast forward to January 2010. 2 months post TX I ran 1 mile. I wasn't winded at all. My stupid legs couldn't keep up because they had never been conditioned for running...and I was pretty immobile for the 6 months before TX.
As for the meds, I didn't really have much in the way of side effects 2 months post. I've had no problems building up muscle because of the insulin I'm taking because of the prednisone. My ligaments and tendons are just fine and dandy.
So far, 6 months post, I've run as much as 6 miles, no problem. I stopped at 6 because I got scared I was going to hurt myself. But I was fine. At the moment I'm letting a shin splint heal (IMAGINE THAT?!?!)...but on Sunday I'm running in a charity road race my wife created for CF and it will be 4 miles.
If you want to run after TX, my advice is to keep walking before TX. If you walk in, you'll walk out. Then you can RUN.