Hey... my first post. I just registered to try to help answer your question.
I purchased a Kindle3 a few days ago myself and bought the lighted case the next day because it felt too vulnerable without the case. In the store they didn't have any on display and I hadn't yet noticed the slots on the side and I was envisioning some insane induction loop setup
and realized that I'd allowed my imagination to run wild once I realized how it really worked.
Anyhow, the hinge connections are actually rather simple. The bottom one slides into the slot and rotates in (apparently against a spring loaded connector as you rotate the device into the upper clip). The top clip is spring loaded and shaped more like a ratchet mechanism. I saw the teardown pictures that seem to imply that there is a multi point connection, but IIRC there is a solid connector for the top and a solid connector for the bottom, so the two pins are probably just redundancy, I suspect + & - are the two separate hinge clips.
Here's a picture that I found online:
http://www.zatznotfunny.com/2010-07/...e-cover-hinge/
I lost my Kindle today (I was afraid this'd happen) because my gf decided that she wanted it for the day... HEY, IT WAS **MY** KINDLE!! Looks like we'll be a two Kindle household soon. Once I get it back tonight I can take pictures or measure the size of these pins with a caliper if you'd like more info. Reply here if you're still looking for more...