If she ingested it last night and has been acting normally, I think you may be in the clear (a quick call to your emergency vet probably wouldn't hurt just to be on the safe side). I found this article on an ingredient found in gum that could potentially be harmful to your dog, but it also says that any symptoms usually appear within half an hour of injesting. Also - I'm not sure if Orbit gum contains Zylitol.
http://unconditionallove.zaadz.com/blog/tags/gum
She probably threw up the gum because she couldn't digest it - and if she ate a whole pack, well too much of anything can make anyone feel sick right?
Take a peak at the article - I hope this helps some....