Some good news from my side.
I did two things today.
1. Installed the WiDi software from the Dell site.
2. Modified some registry keys as suggested here.
After doing step 1, I rebooted and tried connecting, still no luck,
After doing step 2 and a reboot later, WiDi utility finally picked up my TV in the list (for the first time ever after moving to Windows 8).
It asked me to reset the wireless display profile by deleting the TV entries from Devices. Once that was done, it prompted for the PIN but it failed to connect the first time.
Then I went to PC and Devices and searched.. then it detected the TV and connected and I was able to get the same behavior I had in Windows 7. I can use the TV as a second screen just like I would connected with a cable. I am a happy man now. Hope this continues to work this way. :-)