In Outlook 2010, you can paste something and an icon appears next to what you pasted letting you know you have additional options. You can activate the paste special context menu by hovering the mouse over the icon or hitting CTRL. In Outlook 2007, the icon appears, but I can't find a way to activate it other than clicking it with the mouse. Is there a keyboard shortcut key to activate this menu?
Unfortunately, no. Pressing Ctrl to activate the Paste Special menu is a feature newly added to Office 2010.
Source: Office 2007 Paste Special - no mention of Ctrl and does not show the clipboard and (Ctrl) icon, just the icon
Edit: You asked specifically about activating the context menu, but there is a general shortcut for Paste Special which is Ctrl+Alt+V: Source