All,
As a Tiddlywiki super user (not a coder) and an IT professional with some professional security expirence I have spent sometime looking into Tiddlywiki for teams. Bob is already appropriate for fully trusted teams if it continued recieving updates at least. More people should fund Jeds efforts to support bob as I do myself a little.
Bob is Suitable on the LAN or via VPN, I would leave it to others to comment on internet facing security.
Although a user managment layer would be good, this can be built using existing tiddlywiki features as long as you trust your users to some extent. I have researched this extencivly and done a proof of concept for most of the needed components.
I also have a proof of concept for multiuser single file wikis using serial editing. Ie check in and check out.
Some limited private content on a shared wiki is possible, although larger volumes of private content may be better retained outside the core wiki. There are some smart ways to do this which I will not detail here.
Like all solutions we always need to start with realistic business requirements even more so with security needs. There is quite a big range between a simple user selection and a very secure environment and the needs drive the solution. It is my informed view, that especialy with already trusted teams, we already have the capacity to address a large percentage of the possible senarios. If you start undertaking a review of requirements for a team solution you quickly discover there is a vast range of details and circumstances, degrees of risk and comfort with different requirements.
There is already a large number of internet facing secure solutions depending on the requirements, but not multiuser high security.
I am confident we can already address a large number of the multiuser and security issues to deliver practical solutions. For me however I do not want to work on this on my own and I must find an income.
If you have a genuine interest in collaboration or the capacity to fund such an activity please contact me privatly.