can licenses (e.g. the LICENSE file in an open source project) themselves be licensed

@unnick i think most are? most licenses license themself though (the part about you being allowed (and, required) to copy the license, and do whatever stuff).

@unnick Yes. For example, the first line of the GPLv3 (after the copyright notice but before the preamble) is a license for the license:

Everyone is permitted to copy and distribute verbatim copies of this license document, but changing it is not allowed.

(Although the FAQ clarifies that you can in fact create modified versions of the GPL, provided you change the name, remove the preamble, and sufficiently alter the wording of the instructions-for-use at the end and make it not mention GNU.)