We're running WP 2.9.2, just upgraded yesterday. Now it appears we have been hacked.
From some external sites, links to our WP site redirect to a malware site [link to malware site removed]. This doesn't happen when typing in our WP URL directly, nor from all external sites, but once it happens from a site, it happens repeatedly.
I can't find any redirect commands in our installation (eg in .htaccess), but I'm not a web expert. I'm reluctant to post our URL, but here is a screen shot of HttpFox header information from one of the redirect events: