The creator of Skype Trojan decided to publish the source code of his program that is able to intercept VOIP communications of Skype.
Nice intentions but bad execution
He pretends that his first goal is to allow antivirus software companies to update signatures to be able to detect it more easily.
This trojan records your VOIP communications before their encryption and sends them to a remote computer, allowing a third party to listen without anyone knowing.
The publication of the source code to antivirus software company is certainly a good idea, but it's gonna also inspire hackers to invent alternatives and this type of program will proliferate.
The rumor says that this trojan would have been ordered by the swiss government, when the creator says in an interview that the german government would have ordered the same kind of trojans.
Anyway, it is strongly recommended to companies and individuals to pay attention and update their security systems.