Having a HTC Dream, also known as the T-Mobile G1 and being a computer guy, I naturally decided to "root" my phone using the Cyanogen Environmental builds. (Stable can be found here) | (Experimental can be found here)
One of the cool features of the build, is the ability to re-partition the sdcard for putting apps on to the sd card (apps2sd). While the ROM doesn't partition for you, it does automatically install the apps to the sdcard as long as there is an ext2/3/4 partition setup on the sdcard. If you would like to know how to create the partition, check out this thread which explains how to do it from your phone.
Recently updating to an experimental Cyanogen ROM build, I noticed a few weird issues and decided it was time to wipe all of the data and start over fresh. While a regular wipe will reset the phone back to "factory defaults", it does not erase the apps on the SD card. Thinking one or some of the apps on the sdcard might be causing my weird issues, I wanted to erase everything from the apps2sd partition of the sdcard. Fortunately, I ran across a thread on the XDA forums that explained exactly how to go through the process. I tried searching online for the solution before reverting back to the thread, but found nothing which is why I decided to blog the instructions on how to do it (for future reference).
I am not to be held responsible for anything that might go wrong! Use this at your own risk and backup your sdcard!
Here's how to wipe the apps2sd partition on a Cyanogen ROM:
mount -o rw /dev/block/mmcblk0p2 /system/sd cd /system/sd rm -r *
At this point, you should be back at the main recovery menu where you can either flash a new ROM image, wipe back to factory defaults or reboot the phone.