Further to this issue to confirm our diagnosis:



http://developer.apple.com/mac/library/releasenotes/Cocoa/AppKit.html

Backward Compatibility

One backward compatibility mechanism that is occasionally used in the  
frameworks is to check for the version of the system an application  
was built against, and if an older system, modify the behavior to be  
more compatible. This is done in cases where bad incompatibility  
problems are predicted or discovered; and most of these are listed  
below in these notes.

Typically we detect where an application was built by looking at the  
version of the System, Cocoa, AppKit, or Foundation frameworks the  
application was linked against. Thus, as a result of relinking your  
application on Leopard, you might notice different behaviors, some of  
which might cause incompatibilities.

...

NSApplication application menu item title (New since WWDC 2008)

In Leopard, the first item in the main menu (the application menu)  
would have its title modified to the empty string. In SnowLeopard,  
this is only done for apps linked on Leopard or earlier: new apps will  
not see this title modified. The title of the this menu item is  
ignored for display purposes - the application menu always reflects  
the application name.