I registered for the lotto drawing this afternoon. It's going to be interesting on how the lotto system works out.
It is available to US citizens, but there are asterisks. It is basically available until it is not. If a branch of the government like the SEC states that US citizens are not eligible, then everyone from the US will be removed from the lotto drawing. (Which is March 31st @ 18:00 UTC)
I almost get the feeling they know the Gov. will not allow US citizens to participate. But this is a golden opportunity for them to get your Neo address, email, and get you to install their chrome extension.