Slacker has put out an update for its popular Slacker Radio iPhone app complete with a clever feature that actually lets you cache music stations so that you can listen to them anywhere—connected to a network or not.

The app's free, but you do need a Slacker Radio Plus subscription which will run you at least $4 per month. For that price, you'll get these features:

- Cache stations to iPhone, iPhone 3G, iPhone 3GS and iPod touch**
- Enjoy Slacker radio stations even without a wireless network
- Greatly improved battery life
- Unlimited song skipping
- Ad-free listening
- Complete song lyrics
- Unlimited song requests for creating stations
- Music library featuring millions of songs
- No listening limits
- High-quality stereo playback
- Over 120 professionally programmed genre stations
- Create custom stations based on artists or songs
- Fine tune stations on-the-fly to play more of the music you like
- View artist biographies and photos
- View album art and reviews
- "Peek Ahead" artist and album preview
- Pause and skip songs
- Rate songs as favorites
- Ban the songs and artists you don't like

The Slacker Radio 2.0 update should be in the iTunes App Store now and a free 14-day trial of the Radio Plus subscription service is available through the Slacker website. [iTunes]