Skype was sadly afflicted with a software hiccup recently that caused IMs between contacts to get mixed. The bug only triggered if the Skype client crashed during an IM session, and upon rebooting the last message typed or sent was delivered to an unintended contact. In only a few days time the company has issued their first hotfixes for the problem. They are available for the most recent Windows and Mac versions on the Skype Downloading page.
The issue was first noticed by a Skype user who quickly reported it in the support forums. Skype issued a statement reporting that the specific circumstances of the bug indicated that likely only a small number of people were affected. However, the company has over 40 million users, so let's hope small is truly small.
If you've ever read WrongNumberTexts.com, then you know how awkward, hilarious, embarassing, or potentially damaging it can be for an unintended recipient to recieve a message, so it's comforting that Skype was able to get these fixes out to their customers so rapdily.