Archos has officially made Android 2.2 available for its generation 8 tablets (Archos 28, Archos
32, Archos 43, Archos 70 and Archos 101). The firmware is available here, or you can select Settings->About device->Firmware update.
Once you have upgraded to Android 2.2, you can also install the Android Marketplace, by following the directions in this forum post.
Also, here is a video showing off Android 2.2 and the Android Marketplace: