Description
bool 
is_link ( string filename )
     Returns TRUE if the filename exists and is a symbolic link.
    
Note: The results of this 
function are cached. See clearstatcache() for 
more details.
Tip: As of PHP 5.0.0 this function
can also be used with some URL wrappers.  Refer to 
Appendix M for a listing of which wrappers support 
stat() family of functionality.
     See also is_dir(),
     is_file(), and readlink().