Around 11:00pm last night I found the cause of the “Codesign” issue I mentioned in my last post which turned out not to be a codesign issue at all.
Awhile back I wanted to change the name of the application so I modified something in one of the project/target/executable property lists and got what I wanted so I paid it no more mind.  This worked fine with the previous build of XCode.
With the latest build however, not so much.  After beating my head on the desk trying to get the app to build and run on my iPhone, I switched over to the emulator and noticed a subtle problem with the path the debugger was trying to load the executable from, it was trying to load an executable with the original name of the application.
I searched the GUI for somewhere that this name was stored, or where I could override it, with no luck.  Finally I ripped through the project files (inside the xcode project bundle) and sure enough, the original executable name was all over the place.  A quick search-n-replace and rebuild and everything was square…
…at least with the build (I’m having another new problem under 3.0 but I’ll talk about that in another post).
So the culprit is a change in the way XCode is reading the executable name out of the project files.  The codesign error was a false-positive caused by the fact that I had an older version of the executable (under the original name) out in the build directory and it was trying to install this on my iPhone.
Most “bugs” are like this, which is why debugging is a skillset all its own.