i was also unable to update to Facebook 1.4. i'm running uncommon sense 1.0. to fix it, i manually renamed the Facebook APK using the following steps: plug phone into computer via USB, reboot into recovery, mount the 'system' partition', open a command prompt, run adb shell, and run 'mv /system/app/Facebook.apk /system/app/Facebook.apk.bak'. this essentially 'removes' the app, without actually deleting the file (just in case you run into a problem, you can rename the file back to Facebook.apk, and the original app is back). i then rebooted the phone, and was able to install the facebook update.
I couldn't update my facebook on Common Sense. I changed to SR 3.3.3 (was already planning for a new look) and the update worked fine. Has to be something with Uncommon Sense and variations of that framework on other roms.
How do you use system/apps.disabled? I can't get the update on my uncommon sense DInc.
I used the Root Explorer app. First create a folder called "app.disabled" (no quotes) within the system folder. After that, go into system/app and find the file Facebook.apk. Then long press on the apk file and select "move" as the option. Move one level up, back into the system folder, then go into the app.disabled folder. Once there, select Paste. Now all you have to do is reboot and its like Facebook isn't installed. After that, I was able to go into the market and install Facebook as if it were never installed, it won't show up as a pending update anymore.
Of course, you could just delete the current Facebook.apk, but it would be a bit tough to get it back if you wanted the themed version again
yepp it was said above, i think alot of people are putting too much thought into this, and i was guilty when the update dropped too, but just delete the facebook app in titanium backup, reboot, and install from the market.