I received emails from Yahoo this morning stating Yahoo will be cutting off ads at 75 characters. They had started this shortened descriptions some time ago but still allowed for the 'long description' and would simply truncate the ad at 75 characters.
Seems now you will not have the option - all ads will use the 75 character limit.
Per Yahoo: "Beginning in late November 2007, if you have created short descriptions for your ads, those short descriptions will automatically be displayed on Yahoo! Search results (currently the short description will not always be displayed) but if you have not created a short description for a particular ad, the long description will be automatically cut off to fit within a 75 character limit," the emails stated.
Why is Yahoo making the change?
"We are implementing these changes to streamline the search results displayed on Yahoo!, making it easier for users to read and absorb your ad messages. Our research has shown that by improving the search experience in this way, advertisers may see an increase in clicks, while maintaining their conversion rates" the announcement explained.