If you didn't make it to SharePoint Connections 2008 this year, we have a little taste of what you're missing. Currently showing on the ITTV.com video site is a roundtable discussion of SharePoint security. Listen to SharePoint gurus Michael Noel, Kevin Laahs, and Dan Holme, all presenters at the show, give a high-level overview of the different aspects of securing your information assets within SharePoint. Learn about topics such as Rights Management Services (RMS), authentication, and authorization and how they relate to SharePoint security. And get the low down on how ISA Server and IAG can help protect your Internet-facing SharePoint sites. Good stuff here. Scroll down to see the video, or go to ittv.net.
And for some further information on the topic of SharePoint security and permissions, check out these additional resources.
Safeguard Your SharePoint Content with Data Protection Manager
Controlling SharePoint Access
SharePointers
Windows SharePoint Services Security Model
SharePoint Security Roundtable Discussion