I continuously monitor bing positions from it's very beginning for about 250 target keywords, I have detailed day by day data for each keyword and position.
The website I monitor positions for - is almost perfect at seo, it is an old website of a very good quality, it has about 60000 pages of superb unique content, thousands of quality backlinks and so on.
Interesting thing happened right after joining webmaster tools and adding(on 22th of July) this website to it. About 80% of my monitored keywords were affected immediately, positions were downgraded almost the same day. Some keywords -1, others -30, but all this happened at the same time.
Anybody can report the same situation with positions after joining bing webmaster tools ?