Here is the announcement straight from meebo:
We made a significant, but not very obvious, change to Meebo with our latest release. Did you notice?
We introduced a feature sometimes called "off the record," which lets you decide on a per-friend basis whether to store your IM history.
Note that the person on the other side of the conversation could still be saving the chat contents. You are only changing the setting for your own chat logs.
Chat logs can be extremely useful as a reference when you can't remember a phone number, need to find a link someone sent you, or if you just need to confirm that you were supposed to meet your friend at 5:00 at the mall(not 3:00 at the park). However, sometimes you might not want to save your IM history.
That's where "off the record" comes in.
To toggle your personal chat logs on and off for an individual buddy, open your conversation history and then select "IM History On" or "IM History Off" at the top of the window.
The chat log icons in both the IM History window and your IM window will change to indicate the current status.
Of course, you can also control whether chat logs are on or off for all users - just go to preferences > im settings from the menu at the top of your Meebo desktop.
You can also delete your entire conversation history for an individual buddy from the chat log window.
So try it out and tell us what you think.
Thanks to Paul and Len for building this frequently-requested item and to David for the cool graphics, and keep on the lookout for a couple more posts about some other recently released features.