Not just GameSpy. IGN is closing down 1UP and UGO as well. Even though I haven't really been much on UGO, I've been a member of GameSpy for a long time and regularly read 1UP's game reviews, so losing both of those is a big blow. Still, the only problem I saw with GameSpy was that it lost relevance the minute Steam and the Wiki initiative hit the Net. What was once a centralized community of gaming websites and networking had to eventually give way to the more decentralized future and the network with the support of the most commercial third-parties.
Overall, this is sad times, but then again, "the times, they are a changin'".