Philip split off his personal domains from those of ArsDigita and photo.net a while back. Originally, his site was intermingled with photo.net and lived on the same machine.
According to the Netcraft What's That Site Running? http://uptime.netcraft.com/up/graph/ service, www.photo.net is now running on AOLserver 3.3.1+ad13/Linux while philip.greenspun.com is still at AOLserver 3.2+ad12/Solaris.
The two machines are one IP address apart, so they're probably in the same co-lo facility.
I don't know why the site was down; philip.greenspun.com is working fine from my machine though (Sat 12:25 P.M. PST).
