Grubwithus is a site that sets up restaurant dinner parties at which strangers can eat with awesome people. Graham is so optimistic about Grubwithus that he refers to it as a potential 'square on the period table' -- a company that seems almost organically preordained, like Twitter and Facebook.
Java is a general-purpose, concurrent, class-based, object-oriented computer programming language that is specifically designed to have as few implementation dependencies as possible. It is intended to let application developers "write once, run anywhere" (WORA), meaning that code that runs on one platform does not need to be recompiled to run on another.
A free software license is a software license which grants recipients extensive rights to modify and redistribute, which would otherwise be prohibited by copyright law. To qualify as a free software license, the license must grant the rights described in The Free Software Definition or one of the similar definitions based on this.