When I reviewed the Panasonic TC-PVT50 series I was annoyed to see that the latest software update caused a banner ad to appear whenever I turned on the TV. It disappeared quickly and only popped up upon power-on, but it was still obnoxious. The first thing I wondered was whether I could turn it off.
Happily, Panasonic built in a way to disable the advertising. It's a simple, albeit buried, menu command. Here it is in a nutshell.
Grab your remote
Hit the main Menu button on the remote (not the "Internet" or "VieraCast" button) or the TV itself.
The main menu will appear, most likely with "Picture" highlighted.
Navigate down to Setup, hit OK.
Navigate down down (or up) to the second screen until you land on Advanced Setup. Hit OK.
Viera Connect Banner command
Hop down to Viera Connect Banner and...
Viera Connect Banner, Off
...turn it off using the left or right directional arrows. Now you can exit the menu system and the next time you power up the TV, banners will be banned.
Main Viera Connect menu banner
The VT50 review sample I tested also has an ad on the main VieraCast home page. Unfortunately there's no way to remove or disable it (the option is currently grayed out on the home page customization screen), but at least it's less annoying than the banner.