Texting iPhone 3G

Set a passcode on your phone and change your text settings and all that will appear is who the text is from.
But if you are putting in the passcode and handing the phone to friends they can easily go to the SMS app and see the texts. Currently you cannot set a separate password to block out specific access to texts. Your best security move if you are worried about this is dont let your friends use your iPhone.
MacPro Dual Core 2.66 Ghz, MacBook Pro 15", iPhone 3G Mac OS X (10.5.6) AEXs, Red 2G Nano, Red Shuffle, 160 GB Classic, White 60GB 5G, Apple TV

Thx Deggie
I think im on my way to privacy.
3495
Windows XP Pro

If you would really like to see a separate text password, send your suggestion here:
http://www.apple.com/feedback/iphone.html
And who knows what 3.0 will bring in this area.
MacPro Dual Core 2.66 Ghz, MacBook Pro 15", iPhone 3G Mac OS X (10.5.6) AEXs, Red 2G Nano, Red Shuffle, 160 GB Classic, White 60GB 5G, Apple TV