My experience with many who at least call themselves libertarian is that they don't really believe in much of anything that restricts their behavior in any way, including fences to keep you off of someone else's property. Maybe they are abusing the word libertarian, just as you said many abuse the word conservative.
People lie. If you buy into it without finding out the truth, it can lead to exactly the type of post you made.
They are. Libertarian is absolutely about property rights, and some of the biggest beefs libertarians have with our government is the extent to which it infringes on those rights.
I do have strong libertarian (little "l") leanings, which is one reason why I respect the rights of copyright holders to release their software under the license of their choice. Of course, that sometimes conflicts with other rights, such as freedom of speech in the case of some proprietary licenses (such as some from Microsoft), so in those cases I will complain. It's not some fuzzy "The leftists are coming, the leftists are coming," but an actual restriction on freedom of speech in order to control what's known about their software.
Of course I know you've been avoiding that latter issue, since you don't want to be seen condemning Microsoft for their unethical acts.