Tips: Manually Install Windows Phone 7.8 with Windows Phone Hacker Tool.

While most Windows Phone devices are getting the Windows Phone 7.8, my HTC Titan II was getting desperate of ever seeing the update notification. Ok, I was desperate :). But that was until I came across Seven-Eighter by Windows Phone Hacker. A tool that updates your phone to WP7.8. Of course, you do this at your own risk, but it worked flawlessly for me. My Titan was running version 8112 before the upgrade. That's a version before Tango. So the update tool will apply all the previous updates that your device did not get. Therefore get ready for multiple updates and reboots before you get to 7.8. It took me 3 reboots to get there. 
Make sure you connect your device to a USB port at the back of your computer. Do not use a USB hub. Close Zune and for safe measure, open Task Manager and kill each and every Zune process.

Update: I successfully updated a AT&T Nokia Lumia 900 using the process below.

This is how you do it:

1. Before you even connect your device or download the tool, we need to verify the language packs installed on the device. This is very important if you do not want the upgrade to fail with dire consequences. So go to Settings > region+language and write down all the languages listed in the Display language box.
2. Download Seven-Eighter here and unzip.
3. Double click Seven-Eighter executable and select the language packages installed on your device and that you wrote down in step 1. Again, this is very important.
   You may be asked to download Windows Phone update tool. Go ahead and install it and restart Seven-Eighter.
4. Click Ok to start the update. Wait until the update applies and the phone restarts.
5. Do not disconnect the phone and verify the version number. Repeat step 3 above until the version number reads 7.10.8858.136.
6. Enjoy Windows Phone 7.8

Source: Windows Phone Hacker