Love it or hate it, the cloud is allowing some incredible things to take place such as being able to offer anyone the power of a supercomputer for pricing in line with a cup of coffee. Barry Levine writes about how a researcher was able to tap into the massive power of the Amazon EC2 cloud to break WiFi passwords at just $2 a pop.
So many passwords are susceptible to brute force attacks where a dictionary is used to generate passwords until it finds one which is correct. This is why some login screens have a CAPTCHA code requirement where a human needs to determine what the code is. In this way, you guarantee that brute force attacks are eliminated.
Another option is to close down a session or lock an account after a certain number of incorrect password attempts.
For chief security officers and IT managers this just means the benefits of the cloud will be offset somewhat by their evil-doing hacker nemesis who will be looking to use the latest tools available for nefarious purposes.