Google has confirmed a bug where searchers are forced through a Google redirect page prior to ending up on the ultimate search result. This only happens when you search for something with a hash, for example a search on [c# language].
If you search for that, you are presented with search results, but if you click on the search results, you are prompted by a Google redirect warning. Here is the path:
You can see the warning by clicking here.
I wonder if people who rank well for # related keywords have noticed a major drop off in referrals from Google?
Google confirmed the bug in a Google Web Search Help thread, saying:
Thanks for reporting this issue. I saw the same redirect page when I clicked on the first result for my [h#] search. We're looking into what might be causing this and I'll let you when we get an update.
Forum discussion at Google Web Search Help.