Over the past few days, I've seen some but not a ton of chatter about a possible update at WebmasterWorld.
The chatter began around July 30th at a high enough level for me to keep an eye on it and it continued through July 31st. Since it is the summer months, often this type of chatter is always a bit diluted. But here are some complaints in the thread:
My traffic has been decimated today across all sites, checking logs something happened last evening UK time.
From the looks on my multiple domains/subdomains, this week is a new Panda sherif in town. A bad one, also...
Also, the tracking tools showed signs up a smallish update:
Forum discussion at WebmasterWorld.