Yahoo and its websites has experienced some performance issues earlier today. Most notable was with the news outlets and Yahoo search for U.S. locations, and the main homepage for Yahoo visitors in London. It also looks like Flickr was down for a bit, as was the Yahoo instant messenger, though everything seems to be working well for me.
Some have been good to note the annual correlation between summer heat and website downtime, as MySpace went down last year and Facebook has had some performance problems of its own earlier this year. While speculation arose regarding the scalability of the social networks experiencing down time, it's unlikely that this would be the case for Yahoo, a long standing-front runner as far as online destinations go. Nevertheless, people tend to notice, and get upset, when sites this large have any down time at all.