Are you a Twitter user? If yes, you probably know how easy it is to interact with the service using the API. Here’s a nice function to split a text into 140 characters (or less) chunks.

function split_to_chunks($to,$text){
	$total_length = (140 - strlen($to));
	$text_arr = explode(" ",$text);
	$i=0;
	$message[0]="";
	foreach ($text_arr as $word){
		if ( strlen($message[$i] . $word . ' ') <= $total_length ){
			if ($text_arr[count($text_arr)-1] == $word){
				$message[$i] .= $word;
			} else {
				$message[$i] .= $word . ' ';
			}
		} else {
			$i++;
			if ($text_arr[count($text_arr)-1] == $word){
				$message[$i] = $word;
			} else {
				$message[$i] = $word . ' ';
			}
		}
	}
	return $message;
}

Usage

$chunks = split_to_chunks(10,"My very long phrase to split");