Rdio is an ad-free music subscription service that is available as a website and has iPhone, iPod Touch, iPad, Android, BlackBerry, and Windows Phone applications.

A few days ago I wrote about how Google and Facebook were in talks to form a partnership with Skype. Looks like those talks have ended because Microsoft is going to acquire Skype Technologies Inc. for between $7-$8 billion according to several sources. Including the long-term debt associated with Skype, the deal is worth about $8.5 billion. This would be Microsoft’s largest acquisition since Yahoo! turned down the $48 billion offer.

Rdio is a social music service start-up that has raised $17.5 million from new and existing investors. Mangrove Capital Partners has joined as a new investor along with previous investor Janus Friis through investment entities Atomico and Skype. The funding will be used to expand their platform and regions. Warner Brothers Records Chairman and Grammy-nominated producer Rob Cavallo is also joining the board of directors at Rdio.

The entrepreneur dynamic duo Janus Friis with Niklas Zennström has officially launched the Rdio service to the public. You may remember Janus and Niklas as the two who started KaZaa, Skype, and Joost. Up until today, you needed an invitation to use the service. The music streaming service starts at a cost of $4.99 per month. However the service is currently open to users in the U.S. and Canada.

Janus Friis and Niklas Zennström are two of the most popular entrepreneurs as they started KaZaa, Skype, and Joost. Their latest venture is a Twitter-like digital music service called Rdio.com.

Niklas Zennström and Janus Friis, the founders of Skype started a company called Atomico Ventures in 2006. The VC firm was started to invest in early-stage European technology companies. Atomico has just announced that they have raised $165 million in funding.

“The type of companies we are looking at are consumer-facing and also small business… that do not need to build up sales forces around the world to scale and grow,” stated Zennström in an interview with the Financial Times. “These are the kinds of companies like Skype, Google and Facebook who, if the business model is really working, they can get large revenues without having to go through too many financing rounds.” [Financial Times]

As you may remember, two months ago eBay was planning to spin Skype into an independent company. The buyers who would take control of Skype from eBay included Marc Andreessen, Ben Horowitz, the Canada Pension Plan Investment Board, Index Ventures, and Silver Lake. However the founders of Skype interrupted the sale by claiming intellectual property infringement on the VoIP technology. The original founders of Skype started a company called Joltid. And Joltid said that they were suing eBay.

The lawsuit has now been settled. eBay will be selling a majority ownership of Skype to the aforementioned investors for $2 billion. Joltid will be licensing the technology to the new Skype buyers. Skype founders Niklas Zennstrom and Janus Friis will get 14% ownership in Skype as a result. Both Friis and Zennstrom will also make a “significant’ investment in Skype too. eBay will retain 30% in Skype and the rest of the investor group will get 56%.

Friis and Zennstrom also filed a lawsuit back in September against former Joost CEO Mike Volpi. Friis and Zennstrom founded Joost several years ago and sued Volpi because of breach of fiduciary duty. Volpi is currently a partner with Index Ventures which is one of the companies buying Skype. As a result, Index Ventures is no longer one of the buyers in Skype. The acquisition is expected to close by the end of this year.

At the beginning of the month, eBay announced that they would be selling Skype to several buyers. The buyers included Silver Lake, Index Ventures, Andreessen Horowitz, and the Canada Pension Plan Investment Board. That sale has been interrupted not by Kanye West, but by the founders of Joost and Skype.

The founders of Joost and Skype started another company called Joltid. Joltid is suing eBay on the basis that Skype is infringing on their technology at least $100,000 times per day. eBay denies the allegations. But Joltid co-founders Janus Friis and Niklas Zennstrom says that their company holds the intellectual property rights to VoIP applications including Skype. Joltid filed the lawsuit against eBay two weeks after the announcement was made that Skype would be sold to the aforementioned buyers.

Today another lawsuit was filed by the Joltid, Skype, and Joost co-founders. Zennstrom and Friis filed a lawsuit against former Joost CEO and Chairman Mike Volpi along with venture capital firm Index Ventures. The lawsuit states that there has been a breach of “fiduciary duty against Volpi, aiding and abetting breach of fiduciary duty against Index, interference with prospective business advantage, misappropriation of trade secrets, breach of contract against Index, breach of confidence, and civil conspiracy.” Volpi had recently quit Joost to join Index Ventures back in July.

Between Index being sued and wanting to buy Skype from eBay, that company is up the creek made out of you know what with no oar. I also think it is safe to say that Friis and and Zennström don’t want to see Index own the company that they built and sold to eBay. Who knows? Maybe the purchase of Skype might be too much of a headache and might the transaction may be aborted. But all the buyers involved have already come to far and won’t go down without a fight.