From the Apache POI web site...

We are currently working to support the new Office Open XML file formats, such as XLSX and PPTX, which were introduced in Office 2007.

Good news if you need to work with OOXML from the Java world.

Shannon Braun has a post about some of the benefits of using WPF for real world business applications.  Shannon has gained a ton of experience working on one of the largest WPF projects that I am aware of.  This post shares a little bit of the value of WPF vs. more traditional approaches.  Good stuff.

In case you haven't seen it, make sure you check out Mircea Trofin's post on LINQ Design Guidelines.  Good Stuff.

Scott Guthrie has a post that starts talking about what's new in Silverlight 2 (note, it is not Silverlight 2.0, its just Silverlight 2 --- apparently some marketing voodoo makes that the right thing to do).  Silverlight 2 brings us much, much closer to parity between WPF and what we can do in the browser.  It's very cool and Scott gives some great info to let you get a feel for how close we are getting.  Tick tick tick as we count down to the official beta release.

ScottGu has a great post covering a lot of the updates that are coming this year to make .NET applications easier to deploy, faster to start, and faster to run.  Good stuff.

Building WPF applications??? Check out the latest updates building composite WPF apps and what is going on with Acropolis by checking out posts by the Acropolis team and Glenn Bock.

Check out the announcement post from ScottGu on Microsoft's MVC work for ASP.NET.

The doctor is in the house with the start of what should be a very good series on working with ItemsControl and its numerous subclasses. 

Ruby is all the buzz.  I was catching up on some blog reading and realized I had missed letting folks know about a nice little write-up Javier posted about working with IronRuby.  Jav is a big Ruby proponent and I'll be doing an interview with him at the Heartland Developers Conference next week.  It should be good.

A 50 minute screencast showing the interaction between dev-design using WPF, VS 2008, and Expression Tools.