You could just avoid having multiple repositories, I don’t really see the point, but I might be missing something.
We have a similar setup at work (although just 1 company!), lots of shared libs, and lots of projects/components that require these libs.
Our structure is like so:
/projects/
—>/foo
—>/bar
/libraries/
—>/vendor
—>/python
—>—>/a
—>—>/b
–>/cpp
—>—>/a
…
lots more stuff!
…
Our projects will then svn:external in the required libs / vendor code.
With regards for continuous integration, wouldn’t you be better with Buildbot ( http://buildbot.net ) or Hudson ( http://hudson-ci.org/ )
At our company I setup Buildbot, which comes with its own source-control poller (SVNPoller). It works pretty well. I would avoid writing your own system if poss. I did this back in the day, and Buildbot does everything and more 😉
With regards to logging, you only need to view logs for a specific project/component/lib right? You don’t need to worry about viewing all logs, so you won’t see logs of things you’re not interested in.
On a final note, aren’t people now moving towards Git instead to SVN? 😉