Pre-order registration starts next week, with actual shipping expected in May. Aaron seems very committed to keeping things very open and Free, even though not every part of the software will be Free at launch, that is simply not possible yet. The ‘market’-client will be GPL’ed at release, encouraging others to make their own implementation, the back-end for the ‘market’ will be opened once it’s been proven to work well (or if the whole thing fails miserably, let’s hope not). 3G and GPS won’t be available on the first models, but I could live with that, though it would be a nice bonus.
Minor bummer is that Aaron is not sure if the HDMI-output will work well at launch, but at least he’s open about it. I’d really like to use that output to hook the Spark up to a TV or my pico-projector. But in the very worst case, if the software flops completely, it’s still an option to install Android on the device, I’ve even seen a video of the tablet running ICS (Android 4.0).