I just got the latest 2.2.7 Market working via the .zip method someone posted over at XDA.
Here's what I did.
1. Make a backup...seriously...
First I tried this...not sure if it had anything to do with getting this working but it could have, maybe?
2a. Go Settings > Apllications > Manage applications and click on the Running tab.
2b. click on Google service framework, Force stop it and clear data and cache
2c. go back and click on market, do the same (Force stop clear data and cache.
3. Go to this thread
New Working Market 2.2.7 (apk attached) - Page 2 - xda-developers and look at post 19 on page 2.
4. Download the .zip
5. Put it on your SD card.
6. Bootstrap and reboot into recovery
7. install the .zip
8. Reboot
9. test to make sure you can install an app with out a force close.
Works for me running rubiX 1.90 (leaked, if that still matters?)
I've installed 3 apps and rebooted twice, just to make sure.
Hopefully that helps some folks.