Due Diligence has a posting on marking up blog postings to indicate the same posting in different languages. (Note that having a standard for indicating MD5 hashs of blog posts is a great idea, independent of the human language issue).

Jäger has a fairly powerful auto-translation feature for viewing blogs in other languages. Alas, it never seemed to generate much interest. We'll be moving a similar feature into Sparks! as a plug in at some point in the future, probably as button to be pushed in the lower left hand corner (under the browser).