Google Update

Some sites have been hit hard by the Google 'Panda' update designed to filter 'low-quality' sites out of search results.
The speculation is that ratio of adverts to content is being examined, possibly 'above the fold' content being particularly targetted. The intention has been to root out 'shallow' sites, but there may well (as with any update) be undeserved consequences for some sites.
I have tested a couple of my own sites and have yet to see any effects, but then I don't build link-farms, and I try and provide good content even when I am trying to optimise revenue from adverts.

Apparently one of the acknowledged losers of the update has been 'Suite101' a site that pays writers for content and then optimises the page for revenue. If they have suffered frim sticking their head 'above the parapet', then it is possible that those trying to make money online from Suite101 could see a fall-off in revenue. Google themsleves seem to be happy to acknowle that Suite101 has been a target, along with 'eHow' and other similar sites.
As ever, the actual algorithm of the update remains secret - which implies that there are some things that you can do that could manipulate the system to your advantage.

It should always be true that a decent site should not fall foul of the Google updates, but there is always a buzz when the updates happen and folks start to see an impact. All-in-all, I haven't been very aware of any massive changes although I am happy to acknowledge that Adsense rate of earnings seems to have dropped since my last payout. Kind of ironic that it is the Google advertising scheme that takes the brunt - after all if I am making less, there is a chance that Google is making less too.