Yep, familiar with how Techcrunch does it.
Rolling Stone uses the FB plugin as well. But do you want your comments posted here visible on your FB wall (if, indeed, you're on FB)? When I asked the same on FB, there were certainly mixed feelings - many people appear to like the separation between their personal feed and their other online 'personas'.
I do want to reduce duplication and make life easier for everyone (many members and I post across PR, FB, Twitter etc) - and using FB for comments is certainly a way to do this. Ultimately, not everyone likes getting involved in forums, and FB integration may be a way of easing this situation. In the short term though Matt, we won't be using the forums to host articles, but it's a consideration for the medium term. But I hope you can find the time to comment on articles as they stand.