A moderator at WebmasterWorld noticed Google stopped using standard URL redirects in the Google search results to track click events. If you hover over the link, it now appears that Google is just sending you directly to the destination URL, without using any click tracking.
But that is not the case. If you look at the source code, it looks like Google is using some type of JavaScript to track the click.
Here is a sample of the code used:
<a href="http://www.google.com/" class=l onmousedown="return rwt(this,'','','res','4', 'AFQjCNG5-9Jej-ukVeakTgwonqt2narbYg','&sig2=4Lwo00y104At7P9SCT7uXA')">
Moderator, jdMorgan, added that he noticed the JavaScript request going to Google but then it is resulting in a 204-No Content response. But then he noticed a request direct to his server with the same referrer (the same/original search results page).
This appears to be a new way of Google tracking click events in the search results.
Forum discussion at WebmasterWorld.