Facebook‘s Connect service — a service that lets other web sites integrate status updates and other features from Facebook into their own interfaces — seems to be gaining traction of late. And it should get an extra boost during President Barack Obama’s first State of the Union speech this evening. Cable news company CNN will be letting Facebook users comment on CNN’s live web video feed of the event.

Here’s how it works: Facebook users approve Connect integration on the CNN site or via CNN’s Facebook app. Then they can comment about the livestream using their Facebook status updates. Users can also comment on each others’ updates, and everything appears back in their Facebook profiles and news feeds, further driving traffic back and forth between Facebook and CNN.

Facebook and CNN offered this feature during Obama’s inauguration speech last month. Then, Facebook users generated more than 1.5 million status updates on the CNN feed — the single largest instance of Connect usage to date that I am aware of. The real-time conversation (and promotion that the CNN integration received within Facebook, and ahem, from other media outlets) also may have helped cause a spike in traffic to CNN’s site that day. Online publishers, including blogs and video sites, have also been busy using Connect since it was first introduced last fall — including an Israeli news portal, which tapped the service during that country’s elections earlier this month, and VentureBeat (see below).

The downside to CNN’s inauguration video streaming was that the video itself didn’t work very well for everyone. Tonight’s second time will be the charm, the broadcaster certainly hopes. You can join CNN’s Facebook group about today’s speech, here.