Wilburforce - 7:33 pm on Oct 8, 2012 (gmt 0)
Looking at WMT data for my site it certainly looks as if something is going on.
Ordering position by the "change" column, the first 25 terms have apparently risen in position by 90 to 600 places, several (I have checked the results to confirm current position) to first-page positions, although rises of e.g. 200 places to e.g. #65 are more common.
This has the look of penalties being fully or partly lifted.
There are 5 pages (25 entries per page) of gains greater than one whole page.
In the opposite direction, there are 6 pages of losses greater than one whole page, with two whole pages (more than 50 terms) that have fallen more than 100 places.
Again, this has the look of penalty rather than normal movement.
Some of the risen terms are similar to the fallen terms, and I can't see what logic - if there is any - might be behind it.
Overall, nearly 18% of terms reported in WMT have changed position by over at least one page, and nearly 5% by more than 10 pages. If this is replicated on other domains, it suggests considerable instability.
Has anyone else found similar movement reported in WMT?