Keep in mind that a "ban" may not necessarily be a ban - may just be a change in the way your site is viewed (by Google). Matt Cutts posted a few weeks ago about how Google changed the way they approached indexed. The basic idea was that you may need "quality" links to get your site indexed fully - that is, if you just have crap links, then Google won't prioritise your site.
This small change means that sites who previously had 10,000's pages indexed, would drop to 1,000's or even 100's.
The point is, that although this seems like a ban or a penalty, it isn't. It's just a shift in priorities.
In my experience, banned sites have PR0, return no results using the site: command and a search for "domain" doesn't return your site in the results.
So, if v7n got banned, the site would be PR0, site:
www.v7n.com would return no results and any Google search for v7n would return sites that contain the text "v7n" and not this URL.
PR0 doesn't mean a ban on it's own - it just means the site's PR is less than 1.
Scott