I thought Protovis might work on IE 7 and 8, or at least on IE 9... but to my surprise, I tried it on all 3 and it doesn\'t work on any (for those example pages... is it a tempo
Protovis requires SVG and IE 6 - 8 do not support SVG. IE 9 does support SVG, so Protovis should work fine on IE 9.
In order to work on IE 6-8 it is necessary for the user to install ChromeFrame, which will install the Chrome rendering ending into IE.
My google tells me you're not alone: http://code.google.com/p/protovis-js/issues/detail?id=15. From here: http://code.google.com/p/protovis-js/updates/list