Seem to finally have ChatTrack working on IE8. The key was installing Opera; it was only when *that* failed in the same way that I realize that it was the server-side code that was wrong (basically had < instead of >= (duh!)). Didn't cause a problem for FireFox or Chrome because they use the streaming code. I trust IE so little that I'd just written off the weird behaviour as an "IE Thing" and was trying to fix it that way (i.e. looking for weird JS failures and the like). I'd likely have spent hours more on that if I hadn't just taken a break to see what Opera would do. Likely won't get mobile versions done for PyCon, so no iPhones for now.
Now back to my presentation.