Bob the warrior, in a post on the Oni Central forum, pointed out an interesting page at Amazon.com. In particular, it's the entry for Oni, listing a price of $49.99 for Macintosh and Windows versions, as well as Windows system requirements and this item of note:

This item will be released on October 1, 2000. You may order it now and we will ship it to you when it arrives.

While of course, all release dates are just whispers in the ether until Bungie makes their own announcement. But this would put Oni on store shelves in time for my birthday. Woo hoo!