I've sadly been neglecting this. Life is busy again, or still, or whatever. Shoot, I'd love to have a couple hours a day to work on this, but I don't. Between kids and homework, normal home repairs and other distractions, I haven't been too consistent.
I did get the SDR receiver, and I played with it. Not sure if it is the antenna, or what, but it only kinda works. It works well enough that I can say the vendors charging more than $100 for a UAT or 1090ES ADS-B in are charging too much. Here is another blogger working on the same idea: http://www.sharebrained.com/2012/05/10/progress-on-my-sdr/
Why do you want an ADS-B only receiver? Not only can you see where the other planes are, but FIS-B will give you weather, and NOTAMS and other good info. It is all broadcast the same way, and it is free to everyone in the air. (XM might be in trouble).
Holy cow, people who did know about open source stuff are suddenly finding out about Arduino's and wanting to put them in airplanes. They can be very useful, with the UAV autopilot stuff, and IMUs and all. Lots can be done, we just have to get to it. There are ARM boards that will host the Arduino shields, and developer software coming soon, so you can have even more power, for only a little money (less than $100).
There have been lots of IMUs around for a little while. Some better than others, and most aimed at the RC plane market. STM is coming out with a dev board that has all the hardware for an IMU. Developer market is all they are shooting for, but the board is supposed to be about $10! http://www.st.com/internet/com/press_release/p3323.jsp . Maybe they will be available by Halloween, and I'll have yet another distraction.
I had a spike in viewers this week. That is good I guess. Maybe eventually all of what I've built will generate enough traffic to pay for some of this stuff.