I am seeing both chatter and tracking tools reporting a possible Google search ranking algorithm update that touched down over the weekend, around April 26th. There is chatter the online forums and the tracking tools are mostly showing changes here as well.
It is super hard to track these with the indexing issues, but those seem to be mostly resolved now, although, who knows what else will crop up around Google search bugs. The last time we reported on an update was on April 8th but that may have been a false alarm.
This update seemed to start late Friday throughout the weekend, which is not too uncommon for how Google rolls out updates.
Here is some of the chatter from WebmasterWorld:
Here are screen shots from the tools that track the Google fluctuations.
Do you notice ranking and traffic changes from this past weekend?
Forum discussion at WebmasterWorld.