Philipp Lenssen at Google Blogoscoped reports that some are seeing Gmail Ads on the Google.com homepage.
Google has started advertising their Gmail service on the Google front-page. You can�t always see it (I can�t); there might be the usual geo-location targeting the US only, or some other randomization.
I am in NY, USA and I do not see it. But someone has:
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update: Aaron Swartz has more on this....