Cisco Systems will acquire open source email and calendar software-maker PostPath for $215 million. Cisco VP Charles Carmel says the company will integrate PostPath, usually called an alternative to Microsoft's Exchange, with WebEx software, which Cisco acquired for $3.2 billion in March 2007. It's only big-spending Cisco's fourth buy of the year — for the networking giant, a tightening of the purse. There were zero tech IPOs last quarter and also relatively few major acquisitions . Which means PostPath investors Matrix Partners, Jafco Ventures and Worldview Technology Partners are no doubt gluttonously bathing in the schadenfreude this morning.