Vinod Khosla, who recently set up his own venture firm, Khosla Ventures, has invested $6.2 million in iSkoot, the Cambridge, MA-based Skype-to-mobile extender service, according to PE Hub. Khosla has become quite active lately and has invested in companies like Slide and iLike.

iSkoot has been getting a lot of buzz, especially after cutting a deal with Skype, and 3, a 3G wireless services provider. Soonr and EQO are other applications that act as Skype-to-mobile extenders.