[gmosx]

posts to google groups show up in devcomments.com, osdir.com, mail-archive.com, etc ranked higher than the original post in google groups.

[Matt_Cutts]

Hmm. That could be if Google Groups has changed the url structure, which could make crawling it harder. Or because USENET/mailing lists don't always have a centralized/canonical location on the web, which makes dupe content more of a potential issue. It's not the usual "Website X copied my website" scenario.

[sequoia]

Getting on a tangent here, but Google has a hard time crawling Google Groups? Have you tried emailing [e-mail]? Just kidding but in all seriousness how is it that a Google property has bad SEO?

[gmosx]

still the sites mentioned above are arguably of lower quality than google groups, there is no reason to rank higher...