With the new translation portal launched, we are now actively looking for additional translators to existing languages (to start with). We have the following languages in the system currently:

The figure to the right is the # of missing translations - the total number of resource strings is a tad over 5000 for SharpDevelop, so you can see that these languages are all at least half-done.
If you want to volunteer your free time to making SharpDevelop fully translated in your language, please send me an email at christoph.wille @ gmail.com (remove the spaces around the @ sign) with your language of choice. Thank you for making SharpDevelop a global IDE!