Now this has confused me no end. . . I noticed today that Yahoo! UK and Yahoo! UK are different in different browsers.
The first link shows a 'classic' Yahoo! in Safari 3 and the second link shows 'new' Yahoo! in Firefox 3. . . if you copy and paste the addresses from one browser to another then you will not get any difference as it automatically directs you to the 'correct' site for that browser. I have included some screenshots below.
I'm going to enter 'geek' mode here, but I suspect that they're Beta Testing a new version of the site and are serving up different versions based on whichever server cluster you hit. We're currently about to start doing something similar to A/B Test some changes to the Checkout process.
By having 2 identifiable versions of the process we'll be able to monitor drop off, throughput, errors etc. and determine whether the old or new version gets us more or less sales. If the new one doesn't, we get to lynch the designer...hurrah!
Nothing says "romance" like a kidnapped injured woman!