Ah, dunno about that one. What version is your PHP interpreter?
PHP 5.0.3:
[kdawg@blizzard(~)]$ php -v
PHP 5.0.3 (cli) (built: Feb 24 2005 12:07:42)
Copyright (c) 1997-2004 The PHP Group
Zend Engine v2.0.3, Copyright (c) 1998-2004 Zend Technologies
[kdawg@blizzard(~)]$ echo '<? print -2^2; print "\n"; ?>' | php
-4
Might as well throw Tcl into the mix as well:
[kdawg@blizzard(~)]$ echo "echo [expr -2^2]" | tcl
-4
[kdawg@blizzard(~)]$
