Updated README

README.md

@@ -22,3 +22,17 @@ This builds the application as `dist/ToggleProxy.app`. You can run it from
 there, or move it to somewhere more appropriate first.
 
 [pyobjc]: http://pyobjc.sourceforge.net/
+
+## NB
+
+On Mac OS X Lion, you might get errors running the application. If that
+happens, first try to find out what the reason is. Run this from the same
+directory as `setup.py`:
+
+	./dist/ToggleProxy.app/Contents/MacOS/ToggleProxy
+
+If you're getting errors about frameworks not found, you might have to
+install a different version of the `py2app` module. I'm using [this
+one][py2app].
+
+[py2app]: https://bitbucket.org/ronaldoussoren/py2app