The Expression Blend Team has put together a blog post of all the training resources and materials out there to get you up to speed on it.
From the post:
Training Resources from Microsoft
Expression Blend and Design Blog: Tips & Tricks
Expression Community
Expression Blend (Online) User Guide
Expression Blend Tutorials
MIX 07/08 Video Sessions
Building Rich Client Experiences with Blend and WPF (by Celso Gomes and Christian Schormann)
Building Rich Web Experiences (by Celso Gomes)
Applications = Designers + Developers (by Celso Gomes and Kirupa Chinnathambi)
Designing Next Generation User Experiences (Johnathan Lansing)
Tutorials (Videos)
A Lap Around Microsoft Expression Blend (Steve White)
4 Visual State Manager Videos (Steve White)
Animation and Media (Peter Blois)
Blend for Programmers (Jesse Liberty)
contentpresenter.com - WPF Video Tutorials (Lee Brimelow)
Lynda.com - Video Tutorials 1, Video Tutorials 2 (Lee Brimelow)
Tutorials (Articles)
Nibbles Tutorials (Celso Gomes)
Collection of Visual State Manager (VSM) Resources (Steve White)
Electric Beach (Christian Schormann)
kirupa.com - Blend + WPF, Blend + Silverlight (Kirupa Chinnathambi)
If you know some that aren't on this list, then email Kirupa (kirupac[at]microsoft.com) to get them added.