I was digging up all the information on this, and I found something on google that explains my findings exactly, but it's written better.
Check this out if you're bored.

http://home.teleport.com/~alliance/2002/april/billboard.html

If you've seen these, or any of the other "Pass it on" billboards or commercials, and have been suspicious about their source, you're not alone. On Feb. 18, "REXELLA" posted to the Portland Indymedia website expressing annoyance ("Gross, isn't it?") about the little girl billboard, pointed out that "The Foundation for a Better Life" is the apparent funder, and surmised, "From the amount of exposure they're able to afford, it wouldn't be a long shot to assume there's big money somewhere. Anybody have any leads?"

As it turns out, several people did have leads that they posted to the Portland Indymedia newswire as they found them. Before long, a money trail was uncovered that led to Philip Anschutz, whom the BBC has described as having "a reputation as one of the hungriest of U.S. corporate vultures."

The relevant thread on indymedia they were mentioning is here:
http://portland.indymedia.org/front.php3?article_id=7597