I could write a lot more about several of those and may do so at some point. If you've been waiting for any of those features, give 5.0 a try. They're looking to get all of those last minute bugs squashed ASAP.
Oh, and speaking of open source... Check out Open Source Goes Corporate in this week's InformationWeek. I had a chance to talk with Larry a few weeks about how much MySQL, Apache, FreeBSD, PHP, Linux, and other Open Source software we use at Yahoo!
About the Author:
Jeremy Zawodny is the author of the popular Jeremy Zawodny's blog. Jeremy is part of the Yahoo search team and frequently posts in the Yahoo! Search blog as well.