Apparently, some messages sent by a device running a recent version of Android can be sent to someone in a user's contact list other than the person which was selected. This is obviously a big problem for many people, especially those that send private messages to friends or family that shouldn't be read by others.
However, that is not the worst bug. Sometimes, after the message has been sent, it even appear to have been sent to the correct person. Engadget write that there is still one way to know for sure who received the sent message by checking out the Message Details screen after sending it.
To top it all off, this last issue appears to only by a "medium" priority for the Google employee in charge of fixing problems which the community report. Google seems to have made some attempts this year to fix these problems in the past, and while we don't know yet if they have fixed with Gingerbread, the thread about the problem in Google Code is showing the issue as unresolved, indicating that it still exists.
If this issue is concerning to you, hit up the link here to the Google Code forums and scroll to the bottom of the page, where you can vote for the issue.
Image from Engadget