Per some feedback, I added instructions to my latest branding article on how to create rounded corners for a web part title bar.
» Part 3: Changing the look and feel of SharePoint components - Intro and Web Parts
Read the complete post at http://feeds.feedburner.com/~r/HeathersBlog/~3/331006043/How-to-Create-Rounded-Corners-for-Web-Part-Title-Bars.aspx