Hi,
I recently had the problem of trying to use discussionplugin on a project I didnt have much time for, so I was in a kind of hassle. anyhow, trac did not generate clickable links in rss feeds (they were basically just file:///trac_env/... links, because "http://my.host.here" got omitted at the beginning of the link).
This happened ONLY in RSS mode, and I fixed it with a stupid workaround by hardcoding (yeah I know, but wth I am really no trac expert) the host name into timeline.py. There just HAS to be a better option than hardcoding; I just could not figure out how to get the base_url from there, but other than that, it fixes the problem for ONE trac environment.
Attached bad patch. anybody: DO NOT USE. JUST LOOK AT IT.