Anyways, going back to the immigration order itself- the full text isn't up on the White House site yet, but I found it elsewhere and read it.
The sections that ban entry probably should've included a caveat for people that have already been admitted (current visa holders etc), and grandfathered them in. I would expect that maybe we'll get clarification on that from the White House Counsel or maybe Trump himself. Without the clarification, there is a potential issue- I haven't researched it thoroughly yet, but the legality of restricting people who are already green card holders is questionable. There is a section in the order that allows Homeland Security to admit people on a case-by-case basis, so that section could be used as a loophole to admit the current green card holders.
People that haven't been granted entry yet, though (i.e. new immigrants), the order can restrict legally.
That's my initial read on it; immigration law isn't my strongest area of the law.. never practiced in that area, but that's my understanding (poe, others, feel free to chime in).
I am interested in what extreme vetting will be. Many of the new refugees that have gone through the long drawn out process of getting vetted and were expected to come to the states are now back in limbo. I know immigration lawyers and know that the process to get here legally is pretty "extreme". It's not like they come straight from Syria. It takes almost two years for an actual refugee to get here now.