So, with considerable regret -- because it looks awesome -- Meteor is unusable to me. I'm certain that many other people are in the same boat.
Its developers say that they've chosen this license because they want maximum contributions from the community. By seriously limiting the size of the community that can use Meteor, they've chosen the wrong way to do it. I would strongly urge them to reconsider their choice of licenses. The MPL[1] would probably be the most compatible with their aims, since it requires any modifications to the core Meteor components to remain open source, while allowing the inclusion of closed-source components without violating an aggressive copyleft. This is a constraint that I would be very happy to live with. Choosing between an agressive copyleft or whatever is behind the mystery curtain labeled "commercial license" is not.
If the Meteor team wants to fix this, they can either:
1. Clearly state that they require a commercial license for commercial use, and state the price and terms of that license upfront (the Sencha approach). Or, better yet:
2. Switch to a license such as MPL, BSD, or MIT.
The former will allow commercial developers like myself to begin adopting Meteor; the latter is guaranteed to produce a much more robust open-source community around it. If Meteor is to become the next Rails, then that's what it needs to do.
Barring this, I'll just wait for other enterprising developers to take the Meteor concept and re-implement it with a more permissive licensing scheme. If Meteor is as good as it looks, then this should happen relatively quickly.