NerdKits goes from beginners to way beyond... We actually publish lots of educational content -- see 18 free videos so far on http://www.nerdkits.com/videos/ -- that show off lots of programming and electronics concepts that push the limits of what most hobbyists are doing with microcontrollers. But we are definitely focused on education rather than selling products to professional engineers! (This is Mike from NerdKits)
I think you've done a nice job of meeting a real gap in the product space. In ten years of watching this stuff (mostly from the sidelines -- anyone more involved please correct me if I'm wrong), I haven't seen much in the way of an all-in-one kit that includes actual interesting components and well-written / MIT-literate instructional content.
The quality online presence -- forums and video tutorials! -- may even be a killer feature.
I don't understand where you get the notion that Arduino is not geared towards beginners.
Arduino centers around pre-built, (mostly) solderless modules, included libraries for doing almost everything complicated, and a high level development environment that abstracts away everything the libraries don't; this is hardly "intermediate level" microcontroller development.
I am in no way disparaging Arduino, by the way! I'm actually friends with one of the guys who develops it, and I'm convinced it's excellent. But "intermediate" it is not.
I'd say, if you want to establish a taxonomy of microcontroller development skill, beginner would include pretty much any pre-built kit that uses a high level language, intermediate would be people who either build their own boards or program pre-built ones in assembler, and advanced would involve discarding both pre-built boards and high level languages.
As good as, e.g., SDCC is, most microcontroller ISAs are just not designed with compilation in mind. When every instruction counts, incurring gobs of overhead to accomodate a calling convention just won't cut it.
EDIT:
By the way, I've done a lot of development with Atmel AVR, Microchip PIC, and 8051 processors, and though the more modern RISC architecture of the AVR is leaps and bounds more friendly to compilation than the PIC, I can regularly beat AVR-gcc and SDCC for code size.
EDIT 2:
I meant to comment in the above that I'm very pleased to see that the Nerd Kit doesn't try to abstract away most stuff like the Arduino kits do. "Just magically working" is fine when you want to bang something out and don't want to know how it works, but in terms of microcontroller erudition nothing beats having to bootstrap yourself.
most microcontroller ISAs are just not designed with compilation in mind
This is true, but the AVR's architecture was specifically designed to be friendly to C. That was one of the reasons I became interested in it: after years of programming HC11s and HC05's in assembly, I had had enough :-)
For me code size has almost never been an issue (and only then when I needed to add a bunch of features without changing the hardware): the MCU memories are getting bigger all the time.
I think Arduino aim to give you a uController to do cool stuff with - without you having to worry about the details of boot loaders.
Either way it's all great - goes back to the days when kids could monitor and control things from their AppleII and C64s rather than just stringing bits of frameworks together to make web pages.
