This has been bugging me ever since we got our Sony Internet TV, and I think I've finally figured out what's going on.
Pandora hasn't been working on the Google TV ever since we got it, it just spits out Unexpected HTTP error occurred code: 417 while StartupAsyncTask and that's the end of that. I have vague recollections seeing this on my phone in the past also, but this doesn't appear to be the case any longer. My phone has version 1.5.2 on it, and the TV has 1.0, so I think I see the problem here.
I took a full packet capture while starting up Pandora, and it was a lot more revealing. I could see that it was my Squid proxy (I transparently run all HTTP traffic through Squid) was barfing. That'd explain the errors I was seeing in Squid's cache.log
parseHttpRequest: Unsupported method '' clientTryParseRequest: FD 153 (172.16.1.5:55001) Invalid Request
Looking at the headers of the HTTP request that the Pandora client is sending out, I see Expect: 100-Continue, and the text that accompanies a HTTP 417 error is "Expectation Failed", so I think this is the culprit.
Searching for Expect: 100-Continue squid turns up information for an ignore_expect_100 directive, but this appears to only be available if Squid is compiled with --enable-http-violations, which the Debian Squid package doesn't appear to be compiled with.
I may have to adjust my transparent proxying rules to not transparently proxy the TV, but this makes me a bit sad.
I tried adding ignore_expect_100 on anyway, and Squid took it, and now Pandora isn't barfing. Yay!