An interesting question was posed to me. "How can I disable DRM for all my Office 2010 applications except for Outlook?" My initial reaction was that this is not possible. I know how to disable it for all Office applications on a client but not pick and choose. A few minutes with Bing and conferring with a peer and I found two possible solutions.

Note: I've not tested these to any great extent. Please test.

Solution One: Disable IRM functionality for all Office applications
Per Office Registry Settings on TechNet there is a value to disable IRM for all of the installed Office applications.
The registy location depends on the version of Office (e.g. 2010) and the architecture (x86 or x64). For my example here I am using the generic HKCU\Software\Microsoft pathing. Please see the TechNet article for the specifics.

To disable IRM for all Office applications on the client set the following registry value.
Name:  Disable
Type:  DWORD
Value: 0/1
0 = No functionality affected by this registry key
1 = All IRM functionality is removed; IRM is disabled

Solution Two: Disable IRM in the GUI for specific Office applications
This solution allows specific applications to have IRM functionality disabled in the GUI. These settings may be managed via GPO or the registry. End users should either see greyed out buttons or they may be hidden. First the Office 2010 Help Files: Office Fluent User Interface Control Identifiers must be downloaded. Then the appropriate GUI options located and disabled. My research has discoved the following settings for Word, Excel, and PowerPoint.

To disable IRM GUI for the desired Office application set the following registry values.
  Name:  TCID1
  Type:  DWORD
  Value: 7990

  Name:  TCID2
  Type:  DWORD
  Value: 7991

  Name:  TCID3
  Type:  DWORD
  Value: 10014

Solution Three: Exclude the applications on the RMS server
This solution does not require any client side management. Use the Exclude Applications feature in the AD RMS console. Enable the feature and add the desired applications to be excluded.