Skype was probably rumoured to be for sale the day after eBay bought it. Recently, at the Q4 analyst meeting, new speculation found furtile soil. I added a little myself.
There is an interesting case for incumbents to take a look at Skype (which neither is a very new idea). Not only would they buy back some lost revenues, but they would also expand internationally (including emerging markets, where they all want to focus their investments at this point - talk about following the crowd). I particularly like the option to buy an international brand name that could be extended to include other services (such as operating the services and the active layer in FTTH networks throughout Europe).
A very valued reader pointed me to a limitation regarding Skype's sale. It has to do with how Silicon Valley seems to work. Apparently, development activity in Silicon Valley is grouped together in a number of clusters, and the sale of proprietary technology that Skype sits on may be limited to companies within the cluster. It could possibly even be a little more pronounced than that: the technology (check out this 1998 company and see what has become of it) serves as the basis for VC groups to set up a range companies. In Skype's case: the Joltid Global Index sofware was first used for Kazaa, then for Skype and next for Joost.
I'm not quite sure how these clusters are formed, but supposedly there is one around Redmond (Microsoft - don't mind the exact geo location), one around Palo Alto (Sun) and one around Stanford (Google, Yahoo!, eBay). This seems to preclude a sale to anything like a European incumbent. But how about KPN - doesn't its iBasis subsidiary have a deal for SkypeOut?