Note that that is the ACM link to the citation; the paper itself is published in an Elsevier journal, and is not available to ACM Digital Library subscribers (like myself.)
You can see the article there if you have a subscription. If you don't have one, you can buy a copy for $40. Otherwise, you can just go to the library.
It's also not too difficult to find a 2005 review copy online. Preprints for the paper apparently date back to 1995.
