(UPDATED) I'd heard from sources that talks between Spotify and labels have been getting more serious recently after months of little movement, but not because they're suddenly loosening their licensing terms. Greg Sandoval of CNet says that the primary reason that the majors may be letting Spotify into the US is because they're being offered big advances.
It makes sense. Spotify has repeatedly claimed that they would launch in the US before the end of the year. And label executives, facing another 2 months of double digit sales declines, would love a cash infusion just in time for their year end reports and Christmas bonus calculations.
Paying big advances and betting that subscriber numbers will eventually catch up is a bold move for Spotify. But almost everyone (including me) that has ever tried Spotify, loves it; and launching prior to new music services from Goolge and iTunes could be Spotify's smartest move yet.