Yesterday Gmail graduated two features from Gmail Labs to the general set of Gmail features–”Don’t Forget Bob” and “Got the Wrong Bob?”–that help you ensure you’re emailing everyone and that they’re the right people to email.
The first feature “Don’t Forget Bob” makes suggestions when you’re emailing someone that is normally in a group of other people you email. Let’s say that you frequently email your boss, your project manager, and two coworkers at the same time. If you start composing an email and add Bob and Steve to the recipient list Gmail will now suggest Angela and Erica too. Conversely if it looks like you’re entering the whole match–Eric instead of Erica–Gmail will suggest an alternative.
The suggestions occur just below the recipient box–as seen in the screenshot here–to activate them you simply click the link to the alternative name. The feature should be active on all Gmail accounts by now; if not, expect to see it appear by the end of the day.
“Don’t Forget Bob” and “Got the Wrong Bob?” Graduate from Labs [The Official Gmail Blog]