Xobni Corp., a San Francisco-based provider of email analytics software, has acquired the IP assets of Firedrop, a failed Web 2.0 company that had raised $100 million before being acquired MetricStream in 2004. No financial terms were disclosed. Firedrop had created something called Zaplets, which placed synchronized applications into email messages. Xobni has raised over $4 million from firms like Khosla Ventures, whose founder Vinod Khosla also had been an early firedrop backer. www.xobni.com