Google is graduating a couple Gmail Labs features that proved quite useful to the ones that have been trying them out, or, at least, that's what Google is saying. “Don’t forget Bob” and “Got the wrong Bob?” are great if you send emails to multiple recipients often, they make sure that you include everyone and that you don't add someone by mistake.
"'Don’t forget Bob' and 'Got the wrong Bob?' are two Gmail Labs features that help prevent you from making two common mistakes: forgetting to include someone on an email, and sending a message to the wrong person with a similar name to the person you meant to email," Assaf Ben-David, Software Engineering Intern at Google, wrote.
"We’ve received quite a bit of positive feedback from people who avoided some embarrassing situations thanks to these features. And today, we’re excited to graduate them from Gmail Labs and start turning them on for everyone," he announced.
The two Labs features are almost two years old, so they probably proved their worth by now. Labs features are often experimental or don't apply to a wide enough audience for them to be included in Gmail by default.
Every once in a while though, Labs features graduate and become part of Gmail. Both new features added to Gmail look at the groups of people you send emails to.
If, in one of your emails, you don't include a recipient that you usually do, you'll get a suggestion indicating that you may have forgotten "Bob." This should ensure that you don't skip anyone, but the suggestions are not intrusive so if the omission is by choice, you won't be too bothered by them.
Similarly, if you suddenly include a new person to the list, and maybe leave out someone else, you'll get a "Did you mean"-type suggestion. If you did do a mistake you can simply click on the person's name and it will be automatically replaced or added to the list.