Jamie, I'm surprised that you (or anyone else) can use Aolserver 4 with OpenACS 4.x. Last time I checked (granted, that was long time ago) a support for extended ADP parser (that, I believe, ArsDigita added to AOLServer 3.x) has been removed (alng with the possibility to register new parsers via modules). This ADP parser is needed by OpenACS 4.x templating system. I've managed to replace AOlserver 4 ADP parser with a ported 3.x parser but that was a bit ugly.
Did the support for extended parser has been restored in AOLServer 4 since (i.e. is anyone able to run OpenACS 4.x on unmodified AOLServer 4)?