I backed up and uninstalled using Titanium Backup, then I downloaded the APK and installed it.
Synced my accounts and good to go.
adb remount adb shell rm /system/app/Gmail.apk pm uninstall com.google.android.gm-1.apk
Running KaosFroyo v35-1, I kept getting "installation unsuccessful" errors when installing from the market or from this downloaded apk (Thanks a bunch, btw!)
Got it to work this way:
1) Using Root Explorer, renamed gmail.apk to gmail.bak in system\app\
2) Reboot phone
3) Ran the gmail.apk acquired here, though I assume that the market installation may work at this step, too.
|apk, download, gmail, gmail 2.3|