But anyway I'd personally stake out the postion that you can safely call bitcoins property...
You can call anything property, the trick is getting enough people to agree.
That's why I brought up intellectual property. IP only 'exists' as property because everyone concerned agrees it is rather then any physical existance of the property.
I think simply calling bitcoins property is the easier leap then trying to extend those 'property rights' into other realms of law. For example the bitcoin theft debate.
I think domain names can provide a good parallel in this example and have been found to be property in several cases.