Not sure how related this is to the google PR update, or if it is simply coincidental, but I am seeing several reports of some significan updates in yahoo rankings.

After checking my sites rankings, I can confirm this for my sites.

Also had quite a few positive changes in google rankings, but I think that is a direct result of the google PR and backlink updates.

significant updates in yahoo rankings

thanks for the heads-up, just checked, my customers' sites are ranking better for their major keywords and phrases

I saw big changes accross Yahoo! for some of my sites also. Some good some bad. Same in G.