I don't work for Gawker, so I don't know the language they're using in-house, but from the outside, I'd describe the way Kinja uses tags and search as being hierarchical.
For example, if you search from Kinja.com, you'll get results from throughout Kinja which includes the advertiser-supported blogs, community forums and personal Kinjas. While if you use the search box on Gawker.com, you'll only be searching Gawker.
Tags work similarly.
For example, though it's not as obvious yet because not that many people are using their personal Kinjas, but http://kinja.com/nsfw brings up all of posts tagged NSFW throughout Kinja, while http://jezebel.com/nsfw produces only the NSFW-tagged posts on Jezebel.
The community forums work the same.
It's also probably worth noting that for example, I shared a post from Kotaku's TAY forum the other day which was tagged "Retro". Even though that post didn't originate in this forum, it still comes up via http://crosstalk.kinja.com/retro, but if you click the tag on the shared post because it's actually hosted on TAY, it resolves to a search on the Kotaku forum's tag.
In addition to general functionality, an understanding of tags is important because if a person wanted to post to Crosstalk before they are registered, they could tag their post Crosstalk and hopefully myself or another Crosstalk author will see it and share it with the forum.