When I started my blog, I read that link targets were no longer supported, so I didn't use them, even though I always loved and expected outside links to open in new windows. Whatever, those wacky w3c people and their standards.
Recently, I was advised by a "real" webmaster to have all of my outside links open in new windows, or I'd lose a lot of visit time. Sigh. I read those arguments that "people" "hate" new windows opening all over the place. Sigh, sigh, sigh.
I don't know what really is right, but I listened and changed a lot of past links, and have been using targets (with rel="external") ever since. But this is hard to do, without Dreamweaver or a prompt in Word Press (hey, there's an idea, but oh yeah, I'm sure WP Peeps want to be "correct" *boo*). And I still have months worth of posts opening in the same window (and thus confusing browsers [as in PEOPLE browsing old archives]). Bum.
A filter (even if not correct) would help me out here. I don't know about the validity. It would also not be too useful with in-blog links (and brings me to the question about whether it can be overridden with typing a target), but it would still be worth it.
Thanks for your help, and I hope you understood that. :-)