The success rate is actually 44%. You can find the stats directly on Kickstarter. http://www.kickstarter.com/help/stats

It's an incomplete list. TKBM has only been tracking projects that ended since mid-June 2012.

According to my numbers, since mid-June 2012, the overall success rate for all projects in all categories has been ~72%. Much higher than Kickstarter's all-time success rate of ~44%.

I've been suspecting their success rate might go up as more people become comfortable with the idea. A lot of small projects should be very do-able if their community is familiar with kickstarter.

Same here. I'm wondering if this is maybe an incomplete list. There have to be more than three failed open source hardware projects out there.