It's not clear that this is truly a Sirius radio unless it's in a car cradle or home cradle. When it's not hooked up to one of its cradles, it seems you can only listen to RECORDED Sirius content (or your own mp3/wma files),and can listen to LIVE Sirius content only when it's connected to a cradle. In this regard, it's similar to the recently announced Samsung XM receiver/mp3 player.
Currently, the XM MyFi (and similar models from other companies) permit you to listen to XM on the go or record up to 5 hours with limited editing capabilities. The recently announced Samsung player may have more sophisticated mp3 capabilities and larger storage, but it apparently won't receive XM live unless it's connected to a cradle, as seems to be the case with this newest Sirius product.
Hopefully, a product will be available someday that does everything: stores large amounts of mp3 files (whether from one's personal collection or recorded from satellite radio) AND permits listening to satellite radio while jogging, etc. THAT will be a product to be excited about, but we're just not there yet it appears.