#8 - Oct. 16, 2009, 7:35 p.m.
Battle.net account passwords are not presently case-sensitive, Saejiin. If you believe such a change would be beneficial, though, please do not hesitate to post within our Suggestions Forum. We're very open to your feedback and would love to hear from you. :)
That said, there's many additional ways to safeguard your Battle.net account beyond case-sensitive passwords—and these ways can help prevent keylogging attempts, too. I'd greatly encourage you to take a peek at the following information:
If you've any additional questions, please let me know!