Ah I looked again, by Gmail calendar is actually an Exchange account. After checking around it sounds like I am not the only one getting the Exchange password rejected since upgrading to iOS4 - so I'll just need to wait for a Google/Apple fix.
Same message on my G3. Just started getting it this morning, but upgraded to 4 when it was first made available. I have tried all possible passwords and nothing has worked.
Got it! The password for my email address at work had expired. I reset the password and the message went away. This is in direct correlation with your email accounts.
This was driving me crazy then i figured it out.
Scroll down on the pop up and it's asking you for the exchange account password for a specific email "bob.smith@gmail.com" or whatever. The password it is asking you for is the password for that account.
I don't even really understand exchange b/c i thought it was a PC thing. reguardless that's the name of the thingy that syncs your emails .. or something..
just in case you can't remember your password for the said email account.. for mac users at least, you can search keychain access using the spotlight feature. (control-spacebar). then once you are in keychain access , scroll down or search the email account , then double click on it,. then click on the box that says "show password". it will usually ask for you computer's password (which is the one you use to open any new application on your computer)
Same problem myself - when I put the right password in I still get the password prompt box.
I have updated to the latest IOS but still the same annoying problem.
Is there anything I can do instead of waiting for the next update?
Thanks