I finally got my hands on the XtremeMac MicroMemo microphone for the 5th gen iPod and I have to say I am very impressed (it took long enough). For starters, this one comes with a little microphone that is on flexible arm that can be pointed in any direction. That can be removed and an external mic or other source can be plugged in. That is where my interest falls off a bit. When i plugged my griffin lav mic into it the sound was not so great. Using it with the included mic makes perhaps the best portable iPod setup I have found. I did a quick podcast comparing the internal and external mic this morning and have posted it here. Take a listen and let me know how you think it sounds and how it compares to the TuneTalk Stereo.
If I had a rating system here I would give a 5 star rating on out of the box performance, but I would dump it down to a 3 with an external mic. All in all, if you need something to record stuff from your desktop this thing kicks butt.