|Downloadable via the Homebrew Browser
Copy the contents of the zip file to /apps/pingus on your SD card or USB device.
Since the Google Code page is a clone of the original project, it has no issues tab yet. Therefore, you'll have to find a way to report issues. I can be found on IRC a lot (e.g. #wiidev on EFNet).
Known issue: the top and bottom are a bit cutoff at the moment.