Well apparently Autodesk has made some considerable upgrades to SBP and from what i've seen, it's something probably worth getting excited about.
Chris Cheung, the SBP product manager for Autodesk has released a full-fledged preview of SKETCHBOOK PRO 2010 HERE. Some of the new tools i'm looking forward to are the elliptical tool which enables you to do precise line work using shapes, and the new texture feature in the do-it-yourself brush tool which now has the ability for the user to create custom brushes. There's also the elliptical ruler which enables you to do draw straight edged lines.
They've also added blur and sharpen tools which will come in very handy. The site has preview videos for each of the new features although, the lack of audio commentary is kind of a let down. (the tools do speak for themselves though...)
As soon as I get my hands on a copy and put it through it's paces, i'll post my review right here.