This is a laundry list of things to think about, plan for, and/or do. Expand any significant points below into their own topics, as necessary, and link to them from here.
Static HTML distribution - use wget with link rewriting? Probably inadequate, leaving content editing links in place and not able to rewrite links in all file formats.
Note: some of this inadequacy could be addressed with a TWiki skin, which can be used to eliminate the editing links. Try appending ?skin=plain to a topic url to see an example. Custom skins are also possible - the Cookbook site uses a non-standard skin called VoidSkin, for example.
Source code distribution - see Source code management above. Can fairly trivially zip up contents of Scm web to make a source distribution. Only works if all significant source code snippets are actually stored there. See IncludingSourceCode.