incrediBILL, moderator at WebmasterWorld, noticed that one of Live Search's bots was crawling through his JavaScript. The bot is named MSNBOT-MEDIA and he noticed that it was accessing JavaScript files and AJAX functions.
He noticed that the bot was triggering actions on a href="#" OnClick="OpenFeedback(1010101234) and he noticed the bot accessing pages that were only accessible through JavaScript or AJAX.
This makes logical sense, as people in the thread note. Much of media content now is accessible only through forms of JavaScript and enabling a bot to access some of that content is important to building a quality media search engine.
Last year, Google officially started crawling JavaScript forms to get to the data that was behind them. More and more spiders are going to start doing this as well.
Forum discussion at WebmasterWorld.