SharePoint Designer 2010 is the tool of choice for the rapid development of SharePoint applications. Using SharePoint Designer, advanced users and developers alike can rapidly create SharePoint solutions in response to business needs. Advanced users can compose no-code solutions that encompass a variety of common scenarios, from collaborative sites and web publishing to Line-Of-Business data integration, business intelligence solutions, and human workflows, leveraging the building blocks available in SharePoint in an easy to use environment. In addition, developers can use SharePoint Designer 2010 to get a quick start on SharePoint development projects.
Here are some useful links for you on SharePoint Designer 2010 I hope you find useful. You can bookmark this page and refer to it later as I will be updating more links as time goes by.
MSDN blogs on SharePoint Designer 2010: http://blogs.msdn.com/sharepointdesigner/archive/2009/11/02/sharepoint-designer-2010-new-shell-tour.aspx
Official SharePoint Designer 2010 page on Microsoft: http://sharepoint2010.microsoft.com/product/related-technologies/Pages/SharePoint-Designer-2010.aspx
Introduction to SharePoint Designer 2010: http://www.endusersharepoint.com/2009/11/12/introduction-to-sharepoint-designer-2010/
Download Microsoft SharePoint Designer 2010 Beta (64-bit): http://www.microsoft.com/downloads/details.aspx?FamilyID=eeda9ab1-ac53-4870-9e1c-38940343d677&displaylang=en
Download Microsoft SharePoint Designer 2010 Beta (32-bit): http://www.microsoft.com/downloads/details.aspx?FamilyID=82df15bd-16a5-460e-a7c4-22599c669bb1&displaylang=en
Changes in SharePoint Designer 2010: http://technet.microsoft.com/en-us/library/cc179083%28office.14%29.aspx
SharePoint Designer 2010 books: http://www.informit.com/store/product.aspx?isbn=0672331055
SharePoint Designer 2010 training: http://www.kalliance.com/microsoft-office/microsoft-sharepoint-designer-2010-training.htm