Not so interesting since it's about 5 companies participating.. It'd be more interesting it if were like the uptime project, with thousands of different servers listing their uptime. There are actually several different ones...
Here's one :
http://www.uptimes.nu/index.php?area=statistics
This one seems more biased towards linux :
http://uptime.0rd.net/page.php?page=toplist
I wonder if there are any good studies.. Ideally ones that classify a system's main purpose (file server, mail server, db server, web server, usenet server, irc esrver, etc) and then have thousands of daily monitored boxes .. would be easy to do with xlm-rpc and rpc.statd.