There's no indication whatsoever that RedHat intends to push forward and complete ACS 5.0 Java. Evidence includes the fact that RedHat has stated their intention to lay off everyone but a handful of folks who work with major accounts such as Siemens (continuing work on their internal Sharenet site, which is ACS Tcl, not Java, based) and the German telephone company.
Unless things have radically changed in the last few weeks, ACS Java is dead as far as RH/aD is concerned.
It's possible that the developers who've been laid off or others might put together an OpenACS-like project to finish it, but I haven't heard of any such plans.
On the other hand, OpenACS 4.5 Tcl is alive and well and has an active and thriving user and development community.
If you like Java, ACS Java might be a choice though the new platform was never completed AFAIK. I'd personally recommend seeking a more mainstream Java-based solution if language choice is what's driving your decision. Forget the ACS and jump into the Java world up to your eyeballs.
On the other hand, if you're attracted to ACS toolkit concepts and language isn't your primary motivation, then there's really no doubt that the OpenACS community is pretty much "it" regarding the ACS these days.
