Site Not Indexed by Google

Indexed by Yahoo and MSN - why not Google?

[Mark_Evans]

Our client has a site that is NOT being indexed at all by Google. Google SiteMaps are set up correctly (have been for 6+ weeks) and we see it's beeing crawled by Google. But still no listings. The client has constructed approx 6 links from other PR5+ domains to this domain, so that Google will "see" it. Additionally, we've built approx 35 external one-way links to the site. Still no indexing.

Yahoo and MSN both correctly are crawling the site and indexing the pages. Any theories as to why Google wouldn't be? It's a new domain for the client, so it might be being sandboxed, but it's been around for several months. No warnings of being blacklisted, so is there a way we can figure out if the site has been blacklisted for any reason?

Appreciate any insight into what might be going on here.