I believe Tamil is supported natively. These are screen captures from Kindle Touch but K4 should have the same support (and Kindle Keyboard too, with latest update). I can't read this, but it looks at least superficially the same as the text on the web page I grabbed it from (using Amazon's Send To Kindle extension for Chrome).
I think the current line up of Kindles (except for DXG) is pretty close to being 'world ready' in terms of script support. Probably does not support Klingon script, however.
Last edited by tomsem; 09-20-2012 at 12:40 AM.