The zip archive, on the other hand, does include SSI.php v2.0.7. I downloaded the tar archive first and then checked the zip archive and found the difference. Seems like you need to automate the creation of the distribution archives ;D
The version numbers aren't updated unless there is an actual change in that file for the patch/update. So in other words SSI.php hasn't had any code updates since 2.0.4, therefore 2.0.4 is technically the latest version of the file, even if the latest SMF version is 2.0.7.
Actually not... There are in fact issues with the tar.gz package :(
We are working on it