Senator Patrick Leahy, who previously introduced a bill that would have actually granted greater protection of your privacy, is re-introducing said bill for discussion on the senate floor next week. The new version however, would allow 22 government agencies access to your email without requiring a judge or informing the owner of accessed email accounts.
Some states require warrants to access email accounts, Kentucky, Michigan, Ohio and Tennessee, for the rest it might be safer to store your personal information (including emails) on a local drive or under your mattress. Protecting your privacy is your responsibility. I have two suggestions how to keep your private emails private:
Use an email provider not located within the United States, making in harder for the apparently overly curious US Government to access your information (runbox.com for example)
Encrypting your email, rendering your email useless for 3rd parties (Suggestions are PGP, VaporStream or PrivateSky).