www.webmasterworld.com - lots of good stuff, and good people still there, but lots of n00bs too. Spend some time, learn the names, and develop your own mental filter to get the best value
www.threadwatch.org - better signal to noise ratio, high quality posts, but not much time for those not up to speed, there's an assumption of competence built in. If you get lost in the heavy threads, you're in the wrong place
forums.searchenginewatch.com - really good posting roster, lower volume than WMW, so easier to filter. Suffers from "tyrrany of the masses" to some extent still
If it's just a case of you needing to reassess how G is working these days, go do some basic research (read up on some white papers, do some comparative searches across G for different terms, across multiple SEs for the same terms, do research on the top 10, and look for the patterns)
I don't think that G have changed anything basic to the working of their algo, but I O think they have some much better filters out there at the moment. They have killed off a LOT of spammy sites recently, and if you have a good appreciation of how their linkage model works, you will see that the ripples can go a LONG way...