You can release source without giving up all rights. For example, to prevent all the stuff you said you didn't want happening, there's a Creative Commons license that requires attribution for any uses of the work and disallows commercial use. (Not trying to talk you into anything. I'm just not sure if you're aware of that kind of license, since it didn't sound like it and those licenses get less attention than the more radical GPL.)
Not really. While companies do stick to the rules when it comes to copying source code or using open source libraries, when it comes to ideas and discoveries once the cat's out of the bag, it's out for good.
It doesn't even need to be done intentionally or maliciously. All it takes is one blog post detailing how something works (as discovered by reading through my code), then another person summarizes that discovery, and the next thing you know, it's all over the web and anyone can & will use it.
I really like your point here, all the disucussion about open source license always makes me wonder how applicable that is in the real world. What it comes down to is that a lone software developer doesn't generally have the resources available to enforce his license, making it rather pointless.
He has. There are projects like http://www.gpl-violations.org/ and people like Harald Welte (and many more) who do have the resources and who will help you (for free).
True, but that mainly helps when it's the body of code that provides the key value, like in a large engineering project of the Linux-kernel variety. If it's the idea and algorithms that are valuable, and the code is a fairly straightforward implementation, then someone can just reimplement it and there's no GPL violation (subject to some gray areas). The only thing that could really keep that from happening is: 1) keep your methods secret; or 2) some variety of software patent.
