Newsgroups in 2011 are an anachronism from the younger days of the internet, and access to them is rather more limited than it used to be. Google provides a web interface to them through Google Groups but in recent years it’s slowly been more and more spam-afflicted.
Is this a indication, perhaps, that TeX use itself is diminishing? I don’t think you can really argue this, as posts on c.t.t. hardly reflect consistent usage numbers over time—if newcomers to TeX and friends find Q&A sites like Stack Exchange I think they’ll be far less likely to want to use Google Groups, which is far more clunky with a poorer signal-to-noise ratio.
But it’s still a shame (or perhaps just a nostalgic twinge) to see a community in decline, even while new ones are coming into being. Despite this, the c.t.t. archives are full of valuable information, and even if new postings diminish the group will live on as a historical record of helpful answers. When in doubt, search!