Seems like America's doors are still wide open to new musical immigrants, because Spotify's stateside foray has just boosted its overall valuation to $1.1 billion. That's based on its two most recent investment rounds, which racked up another $100 million from new and old investors who are clearly convinced that the streaming platform can carve out a niche between existing rivals like Rhapsody and new entrants like Google Music and iCloud. Meanwhile, AllThingsD
