technically (not technologically) speaking, ed stastny (id OED) is the primary maintainer/coordinator/braintrust/janitor. i do a lot of the programming and share some of the day-to-day stuff with ed. there are lots of other sitoans who have (and do) volunteered time to help out in many ways.
ed and i are portland oregon, the server lives in omaha; but sito comes from the hearts and brains of many artists and helpers! (ok, thats a little cheesy.)
when i really think about it, it all seems a little tenuous ... so thats probably why i dont think about it much.
aside: this would probably make a good bullet point for the non-existent sito faq. or, at minimum, should be in the help files somewhere.
(and thanks SO much for the praise and for recommending sito!)
update: i have made a help entry on "who is sito?" to at least begin to address this stuff.