Way back in 1998, I was briefed by a company called eCharge, which had a bright idea to circumvent consumer resistance to online micropayments systems: have people pay through their phone bill instead. The eCharge website is still there today, but hasn't been updated much since 2000, so I guess the idea didn't take off at the time. But I think this is a clue to some of eBay's hopes for its Skype acquisition. People are used to the idea of paying by the minute for their phone services. It's the ideal platform for introducing the notion of payment for online content and services.
As eBay's CEO Meg Whitman confessed today, no one is going to expect to pay for something as basic as a voice call within a few years. But they will still be willing to pay for some of the content and services they receive over that connection, just as they pay extra for calling certain numbers today. eBay, with its ecosystem of buyers, sellers and developers — but no legacy voice business to protect — is perfectly positioned to rapidly transition its Skype customers towards a future when your 'phone bill' is how you pay for low-cost, time-billed (or access-billed) services that you connect to, instead of paying for the physical connection itself. In the Web 2.0 era, those services might be any combination of items — live help, professional services, media downloads, or on-demand applications.
The main obstacle eBay will face is that its ecosystem today trades largely in physical goods. If it's going to realize the opportunity I've outlined, it will have to become a platform that's equally capable of trading services — an endeavor that would bring it up against a lot of competition.