Supposedly what's holding the deal up isn't the price negotiation between consumers and Apple, it's between Apple and the record companies. Nokia, which is planning a similar deal, is reportedly happy to pay $80 per device to the music companies for the rights, but Apple is only offering $20.
Which makes sense -- Apple is the 800 lb. gorilla in the media device market, and so they have the ability in most cases to pay what they want or not bother. If the two sides do come to a deal, however, even the terms of property are still up in the air. A few ideas being bounced around would let consumers keep a certain number of songs even if they changed devices, while some deals would only allow access while the subscription was active.
What this may mean for us as consumers, at least, would be that Apple is planning to bring the iTunes Wi-Fi Music Store to even more devices in the iPod line (or at least expand the capacity of the iPod touch to hold a subscription collection like this). If Apple really is planning to open up their library to a subscription, they should make it as easy as possible to obtain the music on demand.