Google (Mail) Hacks

Googling Google posts about a hidden Gmail operator that lets you restrict your messages to a certain language. It is hidden for a good reason - the automatic detection is not perfect, so not all messages are labeled correctly. How does it work? If I search for lang:ru or lang:Russian or language:Russian, I'll find some of the messages that contain Russian text, which in my case, are all spam. This lang operator can of course be combined with other operators. How would you use it? My main desire would be the ability to block Russian and Chinese spam, which seems to get through only too often. Gmail could provide an option to automatically translate messages written in a language you don't know and add many other useful features from web search (spelling suggestions, query expansion, search refinements). Love Google! Give them your eyeballs! :)