So the product will be open source, but you need a license to download it? So its open source, but not "free". Are there any well known licenses that support this?

I take it that it also means that the license will not allow for you to copy / redistribute Light Table? Does it still really qualify as open source then?

Will they allow for contributors to the core of the product and if so, what rights do contributors need to sign away?

That said, I think its an awesome project!