A thread at WebmasterWorld named Gbot running hard has driven up lots of interest, its on its 9th page now. In addition, this thread has been referenced at other forums, including Cre8asite, under the thread name Raid of the Googlebots. The thread basically discusses people seeing an abnormally high level of GoogleBot hits. I personally do not see much out of the norm with my sites but many are.
In the WMW thread Brett mentions "panic" based spidering, which he describes as "if an index needs to be rebuilt from the ground up in a short time period (aka: the old index didn't work)." Now, I didn't yet read the whole thread but looking over at Barry Welford's post at Cre8asite where he mentions a possibility that Google might be working some relaunch of its engine to counter any of Microsofts future attempts to encroach on its market share.
Some interesting concepts, if true, I wonder what we will be getting from Google.