About a week and a half ago, there was the start of discussion around Google's brand push in the algorithm. Some people started noticing that for some queries (mostly generic queries), more "big brands" were showing up in the search results.
The discussion started at WebmasterWorld and then Aaron Wall provided some statistical data to back the rumors. HuoMah, then chimed in, trying to keep SEOs on their feet and thinking logically about this.
In any event, Matt Cutts of Google made a video talking specifically about this change:
In the video at 1 minutes and 17 seconds in, Matt said, they made a "change" but he wouldn't call it an "update", but rather a "minor change." In fact, in Google they call it the Vince's change (see 1 minute 30 seconds in). In short, he said this impacts a relatively small number of queries, not the long tail ones and it is more about "trust," the "quality" of the page, the page's "PageRank" and "value" then about brands.