Google was indexing that content back when it was still a separate service called Dejanews. Now that the content is incorporated into Google's system, they actually index it less in the primary search results because they have the dedicated groups search.
That is, like the dedicated news search, dedicated image search, etc., the groups search is a secondary index intended to relieve the main index of some of the burden of dealing with that specific type of content.
In the final analysis, Google seems to treat any unpenalized, unfiltered Web document as a Web document. Hence, each page in Google Groups has its own place somewhere in the database and it is considered part of the entire document collection.
There have been some curious comments from Google employees over the past year regarding Yahoo!'s claim to have indexed X billion pages. I infer that Google may have been intentionally de-emphasizing the Google Groups content in their aggregate totals, but I have never seen any indication that the links embedded in that content were not being crawled.
Quite the contrary, I have occasionally concluded that Google found certain pages for the main index because of links in news group postings. The news group articles, once archived on the Web, become Web documents. Once they become Web documents, they are fair game for crawling.
It may be that, now Google controls the archive, they don't have to crawl it because they build the index into their database directly. That may mean that, whereas a few years ago you could post a link to a news group, have it indexed in Dejanews, and Google might crawl it, Google may not crawl the content now.
I haven't tested Google's algorithmic interest in the news groups in at least a couple of years. However, an open-ended
search of Google Groups from the main index produces only a few million results, many of which are not cached.
I infer from that simple test that Google has indeed stopped crawling the archive.
