1) The marketing reason is pretty simple. If Sun does a lot for Ruby, they will win points with Ruby users, so when the time comes to choose an OS or buy servers, Sun would be higher on the list.
2) Every big corporation likes to have it's own technology. IBM is doing more for Java than Sun is, Microsoft has .NET, so Sun can back Ruby and it doesn't cost them much, since most of the work is already done.
3) The 15-20x number was off the cuff. I'm no expert, but it seems like the perceived Ruby slowness actually comes from Rails.
I wasn't aware that Ruby could only run on a Sun machine. It's probably more likely that Sun is sponsoring Ruby for two reasons; one, because Ruby is a hot new technology at the moment, and thus has a lot of visibility; and two, because Sun needs a 'next-generation' platform now that Java is mainstream.
1) The marketing reason is pretty simple. If Sun does a lot for Ruby, they will win points with Ruby users, so when the time comes to choose an OS or buy servers, Sun would be higher on the list.
2) Every big corporation likes to have it's own technology. IBM is doing more for Java than Sun is, Microsoft has .NET, so Sun can back Ruby and it doesn't cost them much, since most of the work is already done.
3) The 15-20x number was off the cuff. I'm no expert, but it seems like the perceived Ruby slowness actually comes from Rails.