Courtesy of a more-than-one-hour long livestream yesterday, now available in recorded form on Twitch.tv, we can get what is perhaps the most comprehensive look at XCOM: Enemy Unknown's gameplay to date. In the video the developers involved showcase two missions and an interlude in the XCOM base, and also take the time to answer a few questions by the end.
In other words, if you're interested in the title, this is a must watch.