From JRR Martin's blog:

http://grrm.livejournal.com/

I had heard the October filming date, but it is nice to have it confirmed.

Now we just need to get some more cast details.

Well that blog was rather confusing. Is 'seven kingdoms' the title? Or was it 'seven gods' or 'song of fire and ice', or do they not know what they are calling it yet? Well it will probably be a while, Metal Gear solid and Prince of Persia have been taking forever and a day so I dont really expect this to get done in any less time.

There's an IMDB entry under "Game of Thrones." As cast information becomes available, I'm sure it'll show up there.

ktom said:

For better and quicker updates on what's going on I recommend the Winter is Coming blog: winter-is-coming.blogspot.com/

IMDB is a wiki so sometimes people post rumors that aren't remotely true. The current cast entries on IMDB are correct though...

Omnicrazzy said:

GRR Martin is giving cryptic clues about the cast so that's why the post is a bit confusing. The series will simply be called Game of Thrones.

The seven kingdoms sevens gods reference is just a play on words and the fact that there are 7 parts cast that he can't reveal before HBO does.