Keeping allow_url_fopen off in mind, using fopen() might not be the best choice ...
If you don't want to use cUrl for one or another reason, what about fsockopen()?
Also, I'd prefer not to waste resources for local URLS (eg. showthread, etc.)
Would be nice if those were detected automatically and the titles retrieved directly rather than forking a new vBulletin instance just to get the title