Do your sites bounce around a ton on some days in the Yahoo SE? Sometimes one of my sites drops 80% of the listings but they soon come back.
Same problem here. Today it will be the first page, second day it will disappear. Have no idea what's wrong with my website.
My pages on a few of my sites have shot up in the SERPS the last few days I noticed the movement about a week ago. Traffic has trippled so instead of being on page 2 or 3 I am on page 1 now for many good search phrases in my niche. These are sites that are about 2 years old.