The new version of Second Life being deployed to the main grid now via rolling restart will *partially* fix the problem with Unicode character handling in IMs. While the worst part of the problem will be resolved, any messages containing Unicode characters will be sent to email instead of through IM due to an architectural issue that could not be resolved immediately. If you do not have IM -> email turned on for your account, the message will be delivered the next time you log in.
We are working hard on a fix for the remaining issue, and hope to deploy it soon (in other words, on or before Monday).