Slacker is intriguing because it caches the songs you haven't heard yet, to create a seamless (and dependable) experience. Many satellite radio users know all about dropouts and the annoyance that they cause (ever been stuck under a bridge in traffic?). This many times is a confusing experience for the non-technical listener, who's accustomed to AM/FM radio.

Slacker instead downloads the radio channels ahead of time, and adjusts each channel based on your listening preference. Regardless if you have a wide range of musical tastes, or tend to listen to the same genre throughout the day, the Slacker Portable adjusts it's behavior based on your behavior.

But the channels are still programmed by professionals (many of whom come from terrestrial, and even satellite radio). The DJs aren't given any limitations in what they can play - Slacker considers them to be the expert, and let's them do literally whatever they want. So it's a human guided radio channel, but with the added layer of your defined preferences. If you "hate" a song, you will never hear it on that channel again.

The easiest way for the Slacker Portable to update its music is through WiFi. But the WiFi only connects once you plug in the device to start charging - preserving precious battery life for listening time instead. You can also initiate a WiFi connection manually for times when you're in the presence of a network (e.g., a coffee shop, friends house, etc).

Once the device connects, it exchanges listening preferences with the server making sure that everything is up to date. So if you listen online and listen on the device, your preferences are carried over from both, making the experience identical across the board. The same applies with any other Slacker-enabled devices.

Slacker is still expecting to ship out within the next few weeks, with additional accessories shipping shortly afterwards. No timeline on the satellite radio car dock just yet.