Last night, reports have appeared on several Russian forums regarding a Skype account hijacking exploit.
The information has been made available on several Russian blogs and is now actively exploited in the wild.
The exploit, which has been available for two months already, takes advantage of the Skype password reset feature. This allows you to reset the password of somebody else's account, as long as you know the e-mail address associated with their main Skype account.
To protect yourself against this exploit, we recommend changing the e-mail address associated with the Skype account to a new, never-before-used address. This should prevent hackers from guessing your e-mail associated with Skype and hijacking it.
Update [14-Nov-2012 10:19am UTC]: the "feature" which allows this bug to work has been temporarily disabled by Microsoft. Link to the Microsoft statement [here].