BGP Security Research Question

I'm a student in college learning about networking and, specifically, BGP. Does anyone have any statistics on the use of S-BGP or soBGP in the wild? I've read a few papers / RFCs on the subject (from Cisco and the like), but I haven't been able to find any information about actual usage. Additionally, do people scan BGP speakers in the same sense that researchers perform scans of the Internet (e.g. zmap)? -- Anthony Weems