This might fit the bill, let us know:
Protector Android App Review by AndroidTapp.com | Android Tapp. Android App Reviews
Protector protects any Android application
with password: SMS, Gmail, e-mail, Settings, Photos, Calendar, Notepad, Chatů everything you want! Want to set PIN-code to private messages? Protect your corporate secrets? Show off your phone to others while keeping private data inaccessible? FINALLY on Android! 99 cents
I just saw a link to this in another thread, thank jsh1120 for the link to it.