The script for s:selectDate seems to choke on the following line (Seam 2B official distribution):
org.jboss.seam.ui.resource.date.calendar.js, line 458:
if (divs != popupDiv && divs.style && !/\D/(divs.style.zIndex))
Apparently, IE doesn't like the "/\D/" part, and, frankly, I don't even have an idea on what this expression is supposed to achieve, otherwise I'd have submitted the patch already... BTW, removing that last expression makes popup to work on IE.
I checked the latest CVS, and it looks like the whole file is deleted now - what happened to it?