I know about Astro Player. Any other apps that feature podcast managment and variable speed playback?
If you'll pardon the "non-answer"...
I wrote Taffy to act as a proxy between your Android device and the podcast provider. It speeds up the podcast before your podcatcher downloads it. There are several undesirable aspects to this approach (hosting not the least among them, nor inability to change playback speed during playback), but I use it every day to listen to several podcasts on my Droid at faster speeds.
Here's to it becoming obselete soon.
My Droid uses BeyondPod, pointed to Taffy podcast feeds, to automatically download all of my podcasts straight to my handset during pre-dawn hours. I wake every morning (and have for months -- Taffy's a pain to setup, but it's pretty smooth sailing from there) to no-hassle, "sped-up" podcasts ready for my commute.
Today, Presto entered open beta. Presto provides a background Service which allows other applications to play MP3 and Ogg Vorbis files on your Android device at faster or slower speeds and/or faster or slower pitches, so that any application can have variable speed playback, as long as the end user has Presto installed. Developers must modify their app for Presto to be used while playing audio, and I've released open source code to make that almost a drop-in replacement for the Android MediaPlayer.
BeyondPod, DoggCatcher, and PodTrapper have all been working with me in the course of development, so should have a version that can use Presto
AntennaPod recently included support for variable speed playback via Presto.