As I understand the CARS if you are cleared to an altitude above 10,000 Ft you may exceed 250 Kts in the climb.
However, Aircraft limitations and Company SOP's may dictate otherwise. It was stated in the Boeing manual for our 737's that we should not exceed 250 in climb until 10,000 feet for birdstrike protection. That was the reason we were climbing at 250 Kts until 10,000.
That had been changed by Company SOP some time ago to what Jamesel has stated.