Google got me to What is Xenonauts Community Edition & how do I get it which links to this thread.
Edit: Or I thought it did, anyway. Looks like it's linking to the release forum instead, not the thread directly.
Nah, ".30 is the latest release" is the info I was missing. All the "how to get X:CE" links pointed to this thread, which only goes up to .27; thus my confusion.