@suppien_ – just an explanation: you cannot *select* objects on multiple spreads at one time.
But: you can address (no selection necessary) multiple objects on all locations in one InDesign file by scripting.
Jump_over did that with "everyItem()" on all "splineItems" of the active document.
"splineItems", that means all regular or irregular objects (graphic lines, rectangles incl. squares, ovals incl. circles and polygons).
"SplineItems" are new to InDesign CS5. So this line of code will NOT work in InDesign CS4 or below.