I know several people that use 223 on deer and even a couple that have used it on elk. In fact I know a guy that used a cast 223 boolit on deer with great results, tho it was a head shot. Its a very popular round and devastating on hogs, and hogs are way tuffer than deer.
I hope it is leagalized, but I have other guns that I will still use either way. I'm more excited about the 35 cal change. I got some wicked 357 cast loads that should be awesome on deer.