Microsoft Network Executive to Join Kleiner Perkins: Russell Siegelman, the former head of Microsoft Corp.'s online service, will join capital venture firm Kleiner Perkins Caufield & Byers on Sept. 1. Siegelman, who helped develop and introduce Microsoft Network last year, will become a partner at Kleiner Perkins and will help the firm find young Internet and software companies to invest in. Siegelman said he'll use his experience in starting and running Microsoft Network, now the third-largest online service after America Online and CompuServe, to find investments. Siegelman stepped down as vice president of Microsoft Network in April, three months after Microsoft decided to revamp its online strategy. He was also responsible for the launch of Microsoft's Web magazine, Slate, which is edited by former New Republic Editor Michael Kinsley.