One of the strengths of the IE 8 browser is that in standards mode it no longer shows the alt text in the tooltip. Previous versions of Internet Explorer showed this text when you hover your mouse over the image — and this behavior prompted many people to misinterpret the alt attribute and to write bad alt texts.
It’s good that they fixed it now, and that IE 8 now behaves like other browsers. The downside of this is that you may need to explain to customers why their clues were lost. At the same time, tell them about writing good alt texts and that they should use the title attribute if they want a clue to appear. However, also make sure that you do not put essential information for the reader in the title attributes .