Via CamWorld: Arsdigita's Information Technology (IT) principles:

• no dependence on Microsoft products
• no servers inside ArsDigita offices (i.e., all servers are colocated at above.net or Exodus)
• any activity that requires collaboration among people will be supported by one of our own Web/db systems
• all documents Web-accessible all the time to everyone

The article includes an insight as to why ArsDigita is predominantly a Sun Solaris outfit rather than Linux. I'll leave you to read the reason why.