According to this latest post on the NuCluez Blog, there's a new "type hint" that's been added to the PHP CVS in the past few days:

function foo( array $a ) { print_r( $a ); } 
foo( array( 1,2,3 ) ); 
foo( "Hello" );'
Array(    [0] => 1    [1] => 2    [2] => 3 )
Fatal error: Argument 1 must be an array in Command line code on line 1

He also mentions that PCRE has been updated to version 5.0.