The three links below an id of "buylink". Using the $$(id) utility method in Prototype does not give you an array containing all the elements with that id in Internet Explorer. The example in the Prototype documentation is a bit misleading there.
The test case embedded in this page goes through each of the links below and styles them orange. In Firefox and Chrome, this works. In IE, only the first link ends up orange.
Thanks to Ben for helping me work it out. I'd been bashing my head against this for a while, thinking it was something completely different.
Firefox 3.0.3:
Internet Explorer 6.0
