BlackBerry Bridge 

Remember when the PlayBook was released, and everyone was all giddy to go and download BlackBerry Bridge was soon as it was live, only to realize that AT&T customers were not supported? Well, after what feels like an eternity it appears as though today AT&T customers will have the ability to download the application officially through BlackBerry App World. Users will be able to access information that is coming to their BlackBerry device, such as emails and calendars, free of charge, but if you want to use the web you will be forced to sign up for the $20 tethering package. Keep in mind, you can still download the "unofficial" version from right here but AT&T could still try to charge you in order to get tethering to work.

Source: AllThingsD

Update - It's official, folks. A tethering plan will be required for web browsing, and full information on the release can be found here