[snotrockets]

Unlike the payphone analogy, where there is metering rules, and as long as you abide by them, you can keep talking, even if it's impolite, there is a legal definition for gifts (it is, after all, a transfer of ownership, and such things are regulated), which, as far as I know, matches the social norm of not being able to claw those back.

[sanderjd]

Ha, except, to go full circle, then if you're using that legal definition of a "gift" requiring a transfer of ownership, it's clear that open source software is not actually a gift, because there is no transfer of ownership.

You can't have it both ways! If it's a "gift" in the colloquial sense of something freely given, then it breaks social convention to claw it back, but it is not illegal. If you want to use the legal definition of a "gift" - ie. for tax purposes, implying a transfer of ownership - then contributions to open source software are not at all a "gift" in that sense.