I can't believe I missed this lower-down in the release:
The acquisition also enables eBay and Skype to pursue entirely new lines of business. For example, in addition to eBay's current transaction-based fees, ecommerce communications could be monetized on a pay-per-call basis through Skype. Pay-per-call communications opens up new categories of ecommerce, especially for those sectors that depend on a lead-generation model such as personal and business services, travel, new cars, and real estate.
So eBay is explicitly saying it will be using/integrating PPCall and extending it into its other properties. The Kelsey Group projected that PPCall could grow to between US$1.4 and US$4 billion by 2009, depending on several penetration scenarios.