1) Assignment to multiple people can be done with a group. The data model supports it, and it's a relatively trivial task to add it to the UI. There's a service contract implementation determining which parties to pick from, we just need to write an implementation that covers the ones we want. Which would that be? All registered users individually, plus OCT? Others?
2) Pagination: I wrote the list-builder with the intent of replacing the bug listing page in bug-tracker. That would give us pagination, and also a table view, something a lot of people have requested. Also, as a temporary fix, I made the index page default to only show bugs opened in the last 7 days, in lieu of pagination. I did this in Feburart, but openacs.org hasn't been upgraded.
3) Complex filtering: Have you seen logger? Something like logger would be easy to do, especially with list-builder. Logger, by default, combines the filters you choose, instead of replacing the filter you have with another one. And a 'clear' link to clear a particular filter. Works nicely, though there's still no way to save your filters. That would be the next step.
4) Color coding of severity codes is a bit tricky right now, given that these are implement with CR keywords, which don't offer any place to store something like that. If we were to rewrite this with the 5.0-only categories package, that might change. Haven't looked at that package at all, though.
Bottom line is: Very good ideas.
I don't see that we (Collaboraid) will have time to get any of them into the 5.0 release, though, given that it's less than one month away, and we should be in code freeze in a few weeks.
But if anyone wants to take a stab at rewriting the bug-tracker index page to use list builder, I'll be more than happy to help out, though. I'd love to see that happen.