Yesterday, Skype's founders sued eBay for copyright infringement, claiming that eBay has been using Skype's underlying technology without permission since March, when eBay's license to use that technology ended.

The auction service eBay bought popular VoIP and instant messaging software company Skype in 2005 for a total of $3.1 billion, but allegedly did not buy the software's core P2P technology, which is owned by Joltid, a separate company run by Skype founders Niklas Zennstrom and Janus Friis.

As a Securities and Exchange Commission quarterly report stated today, "Joltid has alleged that Skype should not possess, use or modify certain software source code and that, by doing so, and by disclosing such code in certain US patent cases pursuant to orders from US courts, Skype has breached the license agreement."

Earlier this year, eBay announced its intentions to spin off Skype, after which, Zennstrom and Friis filed copyright infringement suit against eBay in London. They reportedly even tried to accumulate enough private capital to make a bid to buy back Skype, but that fell through, By the first of September, eBay had found investors willing to pay $1.9 billion for a controlling stake in Skype.

Yesterday's suit pulls those investors into the claim, with the intention of stopping the deal and recovering damages estimated at an astonishing $75 million per day that eBay has run Skype without license.

Because of Zennstrom's and Friis' fight for Joltid's intellectual property, the pair has earned a reputation for suing everyone who attempts to lay their hands on Skype.

In August, LawPundit blogger Andis Kaulins wrote, "In the case of Joltid we have here -- in our opinion -- another typical IP instance of overly greedy intellectual property rights holders who are prepared to try to hold a good share of the world's communication population (480 million registered Skype users) for ransom simply because of their own petty personal selfish interests. We have little patience with such philosophies. IP rights holders in general must be told time and again in strong and stern judicial language that intellectual property rights do not somehow bestow world imperial rights upon them."

EBay spokesman John Pluhowski told The New York Times yesterday, "[Joltid's claims] are without merit and are founded on fundamental legal and factual errors...We remain on track to close the transaction in the fourth quarter of 2009."