Their idea is that it is an HTML5 standard with some additional Javascript hooks for hardware access, so any browser could be the 'core' with only a few tweaks.
"Gecko on top of it. The same version you'll find on a regular Firefox;"
Maybe we're confusing web standards with rendering engines, but this is a product with only one rendering engine.
- Gaia, the top layer, is meant to be engine-agnostic;
- Boot-to-Gecko / Firefox OS, the complete project, is not.
This mostly applies to the Marketplace in how it offers paid apps; we have a decentralized receipt format to let the paid app run on any platform. Unlike any other mobile player, Mozilla is truly making the web the platform. Our platform is not Firefox OS. That's just one device to support open web apps.