Playback on ipod touch
When playing a podcast, a single tap in the album art area toggles the top bar on and off. The top bar shows position in the podcast, has an email icon on the left and a rewind 30 seconds icon in the middle. The icon on the right toggles between 1x, 2x and 1/2x speeds, so check that this is set to 1x. The icons on this bar are different for music tracks than for podcasts (repeat, genius and shuffle).

It's possible the ipod has got into 2x speed mode. I had this the other day, and either toggling the speed mode or pausing and playing again solved it, don't remember which.

Edit: today I had this problem. It seemed that the fast foward button was down, because the pause button was behaving oddly with this weeks "PC Pro" podcast, and the x1 x2 button didn't fix it. Strangley, clicking the home button until the spotlight search appeared seemed to be a temporary fix. Then playing with the transport buttons fixed it completely.