If you try to host the site at
http://mysite.org/blahblah
you'll probably have some errors.
For example, the emails that are sent seem to assume you don't have a subdir, and they'll direct you to
http://mysite.org/CONTROLLER/ACTION
rather than what you'd prefer in this situation:
http://mysite.org/blahblah/CONTROLLER/ACTION
Until this issue is resolved, it's best to use a subdomain rather than a subdir
So instead of
http://mysite.org/blahblah
You'll want to use
http://blahblah.mysite.org/