Merrick here...
I've always been intrigued by the alternate takes/near misses/"what ifs" accompanying huge film and TV projects...so this was of immediate interest to me. Thought I'd pass it along... Michael Chabon's unused script for SPIDER-MAN 2 is online over at mcsweeneys.net. Their introduction reads thusly:

In honor of Maps and Legends, Michael Chabon's first book of nonfiction, which features a pretty amazing three-tiered die-cut jacket by Jordan Crane, and is available now, here—in honor of all that, we present the following Maps and Legends bonus material: Chabon's screenplay for Spider-Man 2. Chabon was the third of four screenwriters assigned to the project; he ultimately received shared "screen story" credit. As far as we know, this script hasn't been seen anywhere else, and it won't be seen here for long.

You can find Chabon's screenplay (in .pdf form)...

HERE!!!

Thanks to everyone who pointed us towards this.