Sure, why not?

And for any non-US users that may be out there, why not join in too? It's sponsored by the US Dept. of Health and Human Services, but there's no reason why women everywhere can't join together and take a challenge, get into better shape, and have some fun while we're at it.
EDIT: It looks like you can't officially register if you're not in the US or a US territory, but if you're a non-US member, there's no reason why you still can't participate independently and chat with anyone here involved in the Challenge.