[jtolj]

I think it was Slicehost that pioneered this approach for VPS hosting companies quite a while ago, although it may also have been Linode as I really didn't become aware of them until Rackspace bought Slicehost and I had to migrate.

[veeti]

Slicehost had it first, then Linode followed.

[tlrobinson]

Yes I was about to say, Slicehost used to do this. I learned quite a bit from their articles.