I was browsing Amazon and I noticed that when searching "1TB" if you hover the mouse cursor over the stars rating image, you only see the score if using IE. If you are using another browser then the score won't show.
A rating of 3.8 and a rating of 4.2 both show up as 4 stars. Of course a 3.8 stars vs 4.2 stars (76% vs 84% score) could make a difference!
This is because the standard way of displaying alt text is only when the user turns off graphics or when the browser is "read out" (e.g browser for users who are visually impaired). IE however, shows it on hover.
So I think if Amazon is to show it regardless of the user's browser, then title should be used in addition to alt. Would you agree?
I'd go for both. Title will show a nice tooltip in all browsers and alt will give a description when browsing in a browser with no images.
That said, I'd love to see some stats of how many "surfers" out there going to a "store" to browse merchandise actually have images turned off or are using a browser that doesn't support images. I think the days where 90% of the population is using a 28k modem to connect to the InterWeb is looooong over.