This has mostly made me want to go look at pymacs again, but at
least it's done. hive.el provides a simple m-x hive-braindump
that prompts (with completion) for tags (comma separated) and then a body, then
calls out to hive-braindump.py to actually do the work.
Next step is to do a tree-browser, but much as I'd like to have it inside emacs, that's going to be painful enough that I'm going to do it in python first (using STFL for a curses interface.)
Other next step is to try using one of the new JSON interfaces to get
the tag list on the fly. Probably also want to come up with some way
of currying hive-braindump itself to make it easier to define
macros and context-sensitive wrappers (though half the value of an
emacs hook is to have yet another place to capture ideas that aren't
in your current context, so that might not be as useful as it sounds
at first.