Patches are always welcome! You'll receive full credit for your contribution, of course. Here's how to submit
Generate your patch against it
Submit your patch as an attachment to a new issue report to http://code.google.com/p/tubepress/issues/list
TubePress can be translated into any language using the gettext framework. To submit a translation...
Translate the words/phrases in this file from English to your native language
Attach the translated file as an attachment to a new issue. Please be sure to note your two-digit country code and your two-digit language code.
You will, of course, receive full credit for your contribution to an open source project! If you're interested in the gory details of how it works, I highly recommend reading WordPress's excellent i18n documentation.