Secret Startup Parameters

/nomutex: allows you to open more than one instance of Google Talk
/autostart: when Google Talk is run with this parameter, it will check the registry settings to see if it needs to be started or not. If the "Start automatically with Windows" option is unchecked, it won't start.
/forcestart: same as /autostart, but forces it to start no matter what option was set.
/S upgrade: Used when upgrading Google Talk
/register: registers Google Talk in the registry, includig the GMail Compose method.
/checkupdate: check for newer versions
/plaintextauth: uses plain authentication mechanism instead then Google's GAIA mechanism. Used for testing the plain method on Google's servers.
/nogaiaauth: disables GAIA authentication method. The same as above.
/factoryreset: set settings back to default.
/gaiaserver servername.com: uses a different GAIA server to connect to Google Talk. Used for debug purposes only, there are no other known GAIA servers.
/mailto email@host.com: send an email with Gmail
/diag: start Google Talk in diagnostic mode
/log: probably has something to do with the diagnostic logging
/unregister: ?
/embedding: ?