OK, did my own research. Looks like you can share them as long as they are all in the same country. The downside being that it looks like all ms points purchases are charged to the main account. So you better trust your friends! I'll have to think about this one.
link to info: http://www.gizmodo.com.au/2010/06/xbox-live-to-offer-us100-gold-family-pack/







