Yes, I'm in IT. Getting on the vendor list seems to happen in two predominant ways - sell your product/service to someone, which gets you entered as a vendor (happens when the PO is cut) or get into an RFI/RFP situation, which can lead to getting into the vendor list if it goes to formal trial, etc. At least at that point you'd have a CNDA (corp non disclosure agreement) on file, which is usually part of the process.