In reply to amydansja:
Did you subsequently have an x-ray and/or a dr look at it? Assuming they said that it's ok to use it, exercise etc I would just have a go and see what it feels like. Obviously start with super easy routes that don't involve using the thumb and build up really gradually - I won't be surprised if over time you get more range back.
I haven't got any direct experience but I did have ligament reconstruction in both my thumbs a very long time ago - not the same as your injury obviously but it hasn't been a problem for me. Also about 6 months ago I somehow managed to punch a hold with an open hand while bouldering - went straight to hospital and luckily there was no fracture but one of my knuckles took a long time to come back to normal. Are you sure yours was broken, could it be that there is still swelling there?