Update: Opening up email to a greater number of characters is a good thing for users, but it's also exciting for spammers. Certain characters - such as ဝ, ૦, ο, and the letter o - look very similar. Too similar, really. So Gmail will now block email addresses attempting to take advantage of this, and it will use the Unicode Consortium's "highly-restricted" specification to do so. Wဝ૦ο!
It may seem to many of us that there are an endless number of email addresses available out there, but if your name contains characters that don't fit somewhere between A-Z, that illusion is shattered pretty quickly.