Is there a way to set Sublime Text 2 (running under OSX) so that it identify MATLAB (.m) files and Objective-C (.m) files automatically? Meaning that ST2 would be able to differentiate between each one and apply it's special syntax highlighting rules. I have already seen this behavior in the all mighty VI and Emacs.
You may want to have a look at /Users//Library/Application Support/Sublime Text 2/Packages/Matlab.sublime-package. It's a simple ZIP file containing a bunch of XML (Plist) files.
In the Sublime Doc for syntax definitions you'd be able to find a documentation of how to create (and edit) syntax definitions.
For an example have a look at the perl syntax definition, it contains a key named "firstLineMatch" which is not used in the Matlab syntax definition. But you could add one and create a file magic for/in your Matlab files.
Update : I just gave it a go and it doesn't seem to work. Do be fair TextMate can't do it either.
Update 2 : After some more investigation: The question about
In the file
and remove it from