While my general units in preferences are set to millimeters, SVG is saved with pixels(!) as units. (Worst units ever? :-))
Anyway, can I change the unit settings for saving SVG?
No. AI always saves as pixels.
Unfortunate choice, if you ask me. One would think that at Adobe (of all places) they should know that pixels don't mean anything in vector graphics. Illustrator CS5 reads the file at 72 ppi, while CorelDraw X4 assumes 96 ppi. CorelDraw, however, at least leaves the user a choice which units the SVG file will use, like inches, mm or cm.
It assumes points on import as well. Even if you defined mm in the svg format. Stupid illustrator.