Timetraveler - 11:20 pm on Feb 20, 2012 (gmt 0)
Just wanted to chime in.
I Also experienced a bottom of page 1 results for main keywords and overall lowering of rankings for 8 year old site (Feb 18). It maintained top positions for 3+ years. Only minor changes to keep content up to date have been done to website.
The only sites that seem to climb rankings for me these days are sites I NEVER touch. Any minor or major tinkering for the better results in worse rankings. Crappy feeling when you want to improve your sites...