A few days ago I upgraded from 6.5x to 6.60B13 Build 4012
I let it install itself using the defaults and retaining my existing settings (as I normally do whenever I upgrade)
Today I noticed that it isn't showing anything in the logging tab - everything else seems to be working normally and it downloads both posts and headers correctly, but NOTHING appears in the Logging tab. Previously I would have two or three thousand entries in the logging tab for just about anything I had it do.
This isn't a big problem for me, especially since most of the log entries didn't tell me much that I understood - but the logging entries were handy when they helped me identify what was going on, especially posts that had been DMCA'ed and not worth spending much time on.