The cd command was a Tcl bug and was fixed in Tcl 8.4.4. The site map is working fine. There was a change in the way ns_eval worked. The ns_eval was removed from OpenACS so it is not an issue.
I don't know of anything stopping OpenACS from running on AOLserver 4 except the lack of SSL. Nsopenssl is not ported to AOLserver 4 yet.
I have installed 5.0 on AOLserver 4 and I will continue to test it so I'll post if anything comes up.
