There are many great new features in the new SCCM 2007 R3 – Beta which is available for download from Microsoft Connect.
Features like centralized Power Management, Delta Active Directory Discovery, Dynamic Collection addition and Prestaged Media OS deployment support are really cool.
There are some other smaller but still great improvements in the SCCM Console like my personnel favorite the Add Resources option, which makes it possible to easy add resources using Direct Membership. There are some really cool tools out there which provides similar features, but not as easy as this.  
Right-click on the Collection you want to manage and there are a new option available, Add Resource.

SCCM_R3b_add resource 




Selecting this will launch the new “Add Resources to Collection” dialog. It defaults to System Resource which is perhaps the most commonly used resource to add in a Collection.  And it is really easy to search for resource without using wildcards like % but it is possible to use wildcards.












It is also possible to Right-click a resource like a computer and use “Manage Collection Membership” to add it to a Collection. Really useful!