Many posts on forums seems to confirm (in my opinion at least) what's happening at Yahoo! and why sites have been bouncing all over the serps lately.
1. To improve their index, Yahoo has been feverishly spidering sites of late. Probably this is to consolidate their position as G!'s Big Daddy seems to be facing some problems.
2. To increase and improve their index, they have (temporarily) lifted many filters which would explain the sudden surge of sites floating back to the top after a period of being banned or were low in the serps. I believe the removal of RSS links are part of this as well. They're probably starting out on a clean slate with a raw index (no filters, no restrictions).
3. After this, they will probably tweak their algos and re-introduce updated.improved filters, and we will see the serps going back to a more stable condition.
That's my humble opinion anyway... but what do I know... my site's bounced betweein page #1 and page #5 (no changes made. was stable at #10 for almost a year) and I can't do anything. My theory seems to console me as I helplessly watch my site ride the Yahoo! Yo-yo!
Let the theories flow... waddya think?