Hi Mathieu,
Not exactly "at a glance" but if you go to the Tools Pane, open the Print Production Panel and select Output Preview, in the dialog that comes up you can select Object Inspector then click on any object in the PDF and the Color Space information for that object will be listed in the text box of that dialog.
Hope this helps,
Dimitri
WindJack Solutions
www.windjack.com
www.pdfscripting.com