There's been a lot of discussion since, including https://news.ycombinator.com/item?id=2445447 and https://news.ycombinator.com/item?id=3489719.
Also, at the time, Dan Shapiro argued against it here: http://www.quora.com/What-do-you-think-about-Joel-Spolskys-a...
I also think the share distribution Wizards of the Coast (Pokemon, Magic the Gathering) accidentally used was interesting: founders had no shares, and worked their way up into the single digits, which supported small, individual investors, but it's probably not recommended if you're planning for traditional investment: http://www.peteradkison.com/blog-entry-2-wizards-of-the-coas... and http://www.peteradkison.com/blog-entry-3-wizards-of-the-coas...