You can now verify the identity of users running your Repl applications, enabling features such as high score tables, social interactions, and multiplayer games without implementing additional authentication systems. A new environment variable `REPL_IDENTITY` is introduced, containing a PASETO token signed by Replit's infrastructure, which can be used to authenticate users and access secrets securely. This allows developers to focus on building their applications instead of managing authentication, with the option to use Repl Auth for web-based authentication. To implement Repl Identity, you'll need to parse Protocol Buffers and verify the signature of the token using public keys injected into each repl.