Can I visit them?

Yes.  They're at the CPMC NICU, which is not an isolation chamber.  They're not sick, and they're not in danger.  They're being monitored because they can't be trusted to remember to breathe (they probably take after their father in that).

You'll need to scrub your hands and forearms as you enter the NICU, and you must be accompanied by one of us.  Two guests at a time are allowed at the bedside, and since we have two bedsides our visitor quota at any given time is four, not including Ginger and me.  (It's one of the perqs of having twins.)  Unfortunately, if you're a kid, you can only enter the NICU if you're a sibling.  We discovered this rule the hard way.  But feel free to come by if you're trekking up to S.F.