Answering to the original Joel's question, after reading other community members answers I have only one point to add, i.e. SOAP integration, but I'm
very, very surprised that no one else perceives this as a problem.
Apart from running the OpenACS native applications, to be really eligible as a portal framework, we absolutely need the ability to cooperate with the existing applications and now I hardly see any alternative to using SOAP.
In fact I'm already using it thanks to the excellent William Byrne's soap-gateway package, but it is unofficial, not even loaded in contrib and lacking the client stubs. Furthermore it uses internally ns_xml instead of tdom and has some limitations with respect to WSDL generation.
For my own use I created the client stubs and adjusted the WSDL generation to my needs, but I think that this is a matter better suited for the core team.