Yes, but on its license page (http://sqlite.org/copyright.html), it has a section for how to obtain a different license for people "are using SQLite in a jurisdiction that does not recognize the right of an author to dedicate their work to the public domain" (among other things).
I didn't know that, but that's exactly the reason that I pointed in the direction of SQLite. I knew it was 'in the public domain', and that their 'full license' would probably have some sort of solution to issues like this.
Obviously this issue is complex enough that they have a page devoted to it.
Right. Specifically, it's the intersection of a public domain license and a program that gets a lot of commercial use (esp. embedded in devices). I know of some other public domain programs (off the top of my head: several of lhf's libraries for Lua), but nothing else that has had the license carefully scrutinized for commercial use.
Also, I've commented elsewhere in thread (http://news.ycombinator.com/item?id=783320) about problems releasing it into the public domain has caused him.