Back in July of this year we reported that a Google has misclassified some of the internet's web sites as parked domains. This caused some honest good quality sites to suffer in the Google search results.
Google confirmed the bug back in July but it took Google several months to fix the issue and for the sites to return in the Google search results.
The issue back in July was caused by an internal Google classifier bug. Google 'manned up' to the issue and told those webmasters who were impacted that it was not "related to anything you've done" and that Google would fix it "over the next couple weeks."
But weeks and months passed and nothing was fixed, at least according to one webmaster.
That webmaster returned to the forums to explain his site did not return for 5 months! Five months due to a Google bug that he had no control over. The lucky thing is that this site was a personal blog and not a real business.
Took about 5 months, from early June until late October (sorry for the delayed update). All I know is what I've read on this thread, that apparently they had a bug with one of their classifiers and that it took a while to fix. I assume that whatever rule was kicking me out was working in most cases, and they decided they were best serving users by keeping that rule in and living with the collateral damage, until they found different rules that got me back (and presumably caused other collateral damage). It's a tough problem, and any algorithm is going to get a lot of things wrong. Some sites have no choice but to rely on Google ... that's where people go looking for information ... but you never know when some side effect of some rule is the death of your site. Sorry I'm rambling. It's a scary problem, and I'm glad it only hit my personal blog and not my business.
Forum discussion continued at Google Webmaster Help.