I just came across your post. I am using the PSoC chips too and I am very interested in a little board. I read a bit through your comments and blog entries.
Here are a few thoughts and apologize if this was discussed lengthy already and I simply overlooked it.
* Why not using a PSoC 5 instead of a PSoC 3? The PSoC 5 comes with an ARM M3 core and gcc as compiler. That means at least from the software side of the PSoC, there is a chance to use only open source software. As for the price, they do not differ so much (Cypress) $18.41 for your PSoC 3 compared to $25.99 for the PSoC5. However, you would get 1 fast SAR ADC, 2 more internal OP-amp and a 32-bit ARM Cortex M3 CPU up to 67 MHz which, compared to the 8051 core, will get you 3 times more MIPS for number crunching. I noticed that many hobbiest people get interested in ARM stuff and hence this board would have double its value. Not only get into programmable analouge stuff, but also as an introduction into ARM architecture. Guess many would overlook the additional $7.5 dollar for these additional features.
* Make sure to select a PSoC which comes with a set of pin-compatible chips. Thus, people might choice to go for one with more RAM,FLASH when prices (hopefully) dropping, or if they want bigger chips for larger projects. This also helps to source for chips if you need to get many boards out.
* One strength of the PSoC is the internal 20bit ADC. However, to make a real use of it, it requires a careful routing in-, and outside of the chip. There is an app-note, which pins should be considered for analogue routing (e.g., avoid pins close to clock lines, etc.)
There is also the need of a good separation between digital and analogue part of the PCB. I would prefer to have one or two dedicated analogue pins on the board (e.g., AD and DA). Maybe using small SSMT connectors, like http://jp.mouser.com/ProductDetail/Hirose-Electric/WFL-R-SMT-110/?qs=x%252biggnnmgNHriCqn0HOi%2fQ%3d%3d
. That would allow people to take real advantage of the analogue part of the PSoC.
* P1 - P1 could be used as normal GPIOs if not needed for programming. You might like to add silk-screens accordingly.
* P12-P12 does not have description. Furthermore, P12-P12 are SIO pins and differ from GPIO pins which might be worse to indicate in some way.
I know that some of the above ideas might break almost all of your design. Just wanted to point them out.
I do not totally understand the way how you are going to upload new bitstreams to the board. If I understood correct, it would require a miniprog programmer. I am not aware that you can use the PSoC USB port itself. During flashing I think the PSoC itself should be laying there like a dead fish, no way the internal USB could work. Even if this would work, given the nature of the PSoC, people could forget to implement the USB module in there designs and loose the programming ability. Maybe I overlooked some recent progress on the Cypress site here.
I have a couple of PSoC Evaluation Kits and they use an external USB chip for uploading. However, they do not provide any way of accessing the USB from the PSoC side (or they changed this recently in the firmware of the UART-bridge).
This would be really a nifty feature to enable programming over USB (via an external fail safe chip) and use the same USB port as PSoC UART during run-time. It would need to switch between this two modes in some way.
Not sure you was thinking about this already.