Signed apps in Tiger

[Ian Wood]

I've not seen this mentioned, but the '300 new features in Tiger'  
page contains:

Signed Applications
Feel safe with your applications. A digital signature on an  
application verifies its identity and ensures its integrity. All  
applications shipped with Leopard are signed by Apple, and third- 
party software developers can also sign their applications.

<http://www.apple.com/macosx/features/300.html>

Ian