Slacker's internet radio service is coming to the BlackBerry this October, and featureset looks to be incredibly similar to the regular Slacker Portable Player features.
As with Slacker's web-based and device-based offerings, you can use the service for free - and the BlackBerry app will be free as well.
Stations are cached on the Blackberry's memory card, so you can play them without a WiFi or 3G connection and don't miss a beat even when you drop signal. Every time you connect the device, the channels will refresh with new content based on your preferences. And just like the Slacker we all know, you can Heart or Ban songs to personalize the music channels to your liking.
Look for the app to be available for BlackBerrys sometime next month.