Source: Gmail's Account Activity Adds Browser User Agent Info to Thwart Would-Be Hackers
Google is now showing more info account activity in Gmail, specifically, there are more details on the browser that was used to access the account.
The account activity tool is useful for keeping track of who logs into your account and from where, and it can be a very useful tool in determining whether your account has been compromised.
Until now though, Google only showed the most basic information on the client used, i.e. browser, mobile or POP3. Now, details such as the browser user agent are showed.