Mentioning someone is an important social act. It's a good way to get on their radar as well as give credit for links or help. If someone does a good job, telling the world about it boosts their ego, helps the community know about their service of offering and also increases your recognition to that person. Telling tens of thousands of people you appreciate someone gets their attention.

Google Buzz has adopted mentions much like Facebook and Twitter. The unique situation (as of Buzz's launch) is that Google Buzz requires those people to be in your contacts at your Gmail account in order to mention them by name.

When you type the @ symbol and start typing a person's name, a list of potential matches are pulled from your address book. The cool thing about this (so long as it works this way) is that you likely know their name as it's recorded in your address book. So, if they go by Bob typing @Bob <space> will likely pull them and other Bob's to choose from.

In a lot of cases, you know people or even email them but don't have them in your address book. Simply go to your Gmail inbox, search for and/or choose an email from them and add them to your Google Contacts. If the email is from an address associated with a Gmail account, you can add them here and mention them later in Buzz. Click on the down button next to the "Reply" button and you can see several options. One of the options is to add them to your Contacts list.

Once that person (and their name/Gmail account) is in your Contacts, you can use the @ symbol and start typing their name to pull them up as a valid Buzz mention choice.