PHP Version Check

gistfile1.php

<?php
...

if ( version_compare( '5.3', phpversion(), '>' ) ) {
	add_action( 'admin_notices', '_myplugin_php_notice' );
	// Do what you need to stop your plugin from loading
}

/**
 * Displays an admin error about needing to update the server's PHP version.
 * 
 * @access private
 */
function _myplugin_php_notice() {
	?>
	<div class="error">
		<p>
			<?php
			sprintf(
				__( 'MYPLUGIN is not active because your server is not running at least PHP version 5.3. Please update or contact your server administrator. (PS: PHP 5.3 is %s year\'s old!)', 'MYPLUGIN' ),
				intval( date( 'y' ) ) - 9
			)				
			?>
		</p>
	</div>
	<?php
}

...

Now, this won't work once enter the year 2100, but somehow I think that's okay!

Thanks!