I rebuilt 3.0.5.600 from the original source file I had downloaded, to make sure I was doing everything right. (The only thing I changed was making a slight change to the url parameters for the {SEARCH} macro; it's a shame that string is hard-coded.)
After I had updated the files, I noticed that, in the Pages Providers list, there was a red "Error" under "Update Status":
I also noticed that there was an error note on the Wiki Version on the Administration Home page:
Wiki Version: 3.0.5.600(Error retrieving Version information)
Does someone know if I did something wrong? The instructions in the Build/Readme.txt seemed a bit barebones, but I believe I followed them accurately. I did keep the original web.config file, but that should not cause issues, as I understand.