Signing into a Google Account for either Messaging / Calendar, fails when the password contains special characters (not all, but for certain chars/combos).
Thread discussing this problem in detail (though it is for TouchPad):
Looking at the application code, reveals that a Regular Expression object is created with our account password, which errors out, if certain combinations of special characters are present in it. Mine had two consecutive * in it.
To see if your password would create a problem, please go to this webpage:
In the box labeled 'Regexp', type your password followed by the '|' symbol and again your password. For eg., if your password is cr**it, type "cr**it|cr**it" (without the quotes) in that box.
If you hit on 'Test Match' button and if you see an alert 'Successful match' or 'No match', then your password is fine and should work with webOS.
Till there is a fix available for this, you can use this method to create a strong password (with special characters) that doesn't error out.