Ed Valentine (sweet name, whether it's real or not) takes a look at the improved Yankee fielding this year through the lens of advanced fielding metrics. It's a good read, and something I'm glad is appearing more often around the web. I really enjoyed the conclusion the article, too, which was refreshingly non-hyperbolized:
"Despite their errorless streak, the Yankees are not a 'great' defensive team. What they are is a 'solid' defensive team, which is a huge improvement over the awful defensive team they were in 2008. Last season the Yankees cost themselves runs -- and ultimately games -- by not being able to make routine plays. This year, they are making the plays they should make and occasionally making a brilliant play.
They may not be the best defensive team in the league. They are, however, helping themselves instead of hurting themselves. That's good enough."
Dan posted last time about part 1, but I think this second part from Jensen might be more interesting to people. He uses Gameday to develop a fielding metric and gets results similar to +/-, and UZR in terms of plays saved. But the run values seem to be a little different.