Loren Baker started a thread at Search Engine Watch Forums named Google Finance Launching or Testing. He describes a pattern he has recently seen in his log files, which may represent Google launching Google Finance. The referrals are coming from google.com/finance (which 404s), the search string is "GOOG" and the URL is http://google.com/finance?q=goog&btng=search+finance (also 404s). Why wouldn't this be leaked earlier in the forums? Well, Loren is one of the few site publishers that is included in Google News and also very involved in the search community. He has an interest in sifting through his log files, like any Webmaster would, plus he is in Google News. One would assume the GOOG related news stories are sprung from Google News, under Google Finance. I tried http://finance.google.com/ and that just times out. Loren has a more detailed write up at his blog on his findings.
We know Google launched the Google Stock Quotes back in May 2004. So maybe this is the next step?
Forum discussion at Search Engine Watch Forums.
