As RateLadder has already spotted, Prosper has filed a Form S-1 with the SEC. In addition, a press release from Prosper also hit the wires indicating that this is, indeed, part of the effort for a secondary market. From the press release:
Following effectiveness of the registration statement, Prosper intends to establish and maintain a secondary trading market online auction platform, or Resale Platform, pursuant to which lenders may seek to transfer borrower notes to other Prosper registered lenders.
The registration statement relates to the Prosper Marketplace Lender Participant Rights, which represent Prosper’s obligations to seek to establish and maintain the Resale Platform and to provide various administrative, clerical, recordkeeping, identity verification, payment processing, collection and other services, associated with $500,000,000 in aggregate principal amount of Prosper Marketplace Borrower Non-Recourse Notes originated and to be originated on the Platform from time to time after the registration statement is declared effective by the SEC.