How to include the built jarfile into eGit -> GitHub?

I'm building a Bukkit plugin, and so far have only the source files & plugin.yml under version control (I'm using Eclipse with eGit). Now I want to add also the actual binary jarfile under version control & share it on GitHub for all my plugin's users, so they don't have to compile everything in case they want to try out my development versions. I cannot seem to find a way to do it - so I must be overlooking something really simple.

Any help would be appreciated.

Scrap that - it was eeasier than I thought! I just had to do "New -> File" in my project and then "Add to index".

No, wait - when I compile the jarfile, it runs great on my machine. The compiled binary is also updated in GitHub - but when I download it back from GitHub and try to run it, I get "Error! Invalid or corrupt jarfile". Why is it corrupted on its way to GitHub and back?

EDIT by Moderator: merged posts, please use the edit button instead of double posting.