While the package is not ready yet for experimental, mostly because there are pending changes in the 3.5 branch, Mozilla released a security update today. So, here are the packages you need to be safe security-wise with Iceweasel 3.6. Please note only xulrunner packages have been updated, as the security fix lies in the xulrunner code.
A known regression of this version is that the icons in the search box on the top right don’t show up.
Update: This regression actually doesn’t exist.