Last week or so RIM announced that its latest OS, BlackBerry 6 was now available for users to download officially for the AT&T carrier. Users can probably download the OS via wireless update or head to RIM’s software page to get BB6 sitting at v6.0.0.526.
The package is between around 160 and 180MB, depending on language options.  Download AT&T v6.0.0.526 Here