The new Yahoo Mail, currently in beta, will be available to all users very soon. An evidence for that is the fact that Yahoo Mail started to display obtrusive ads: along with an animated flash in the right sidebar, you can now see huge ads (like the one for Vonage) that fill an entire page. Ironically, this ad is included in the Spam section.Another usability problems regarding ads in Yahoo Mail Beta. There are two group of ads in most of the pages, one in the right sidebar (animated flash), next to the scrollbars that lets you select a mail or read it. The other group of ads sits at the bottom, right under the navigation, and includes the usual "credit card", "free loan consult" small ads. The problem is that it's very easy to click on the ads by mistake. And if you click on an ad, it doesn't open a new page or tab, the page just replaces the ad in the iframe, so you'll get this funny picture.
Because Yahoo chose to stick with the flash ads, if you move from a page to another (from inbox to the RSS reader, for example), you'll notice a big delay in page loading, especially if you have a slow connection.
And another thing: Yahoo didn't drop the welcome page that announces you how many emails you have, and whose only purpose is to make people click on the ad if they don't have any new messages.