It didn't occur to me to check Helvetica until I saw
that post on slashdot. That is *really* bad. I never liked it, but it's gone from being one of the easiest to read fonts on the Kindle to one of the worst.
Amazon doesn't even use it it for their system font anymore. Look at the Sans fonts on the home page, and when reading the dictionary. Notice the shape of the 'a'. That's neither Helvetica nor Futura, but a new Sans font not even accessible from the font menu!
But silver lining and all that. Maybe all this negative publicity over the state of Kindle font rendering will finally prompt Amazon to do something about it!