Commenting on note http://www.php.net/manual/en/function.sort.php#62311 :
Sorting an array of objects will not always yield the results you desire.
As pointed out correctly in the note above, sort() sorts the array by value of the first member variable. However, you can not always assume the order of your member variables! You must take into account your class hierarchy!
By default, PHP places the inherited member variables on top, meaning your first member variable is NOT the first variable in your class definition!
However, if you use code analyzers or a compile cache, things can be very different. E.g., in eAccelerator, the inherited member variables are at the end, meaning you get different sort results with caching on or off.
Conclusion:
Never use sort on arrays with values of a type other than scalar or array.