you could do it like this so you can do away with the global vars..

on $*:text:/^@url\s(http\x3A\/\/w{3}\x2E\S+\x2E\S{2,3}?\S+)/iS:#:{
  if ($sock(tuly)) sockclose tuly
  sockopen tuly www.tuly.in 80 
  sockmark tuly $+(/bm.php?url=,$regml(1)) msg # Shortened URL:
}
on *:sockopen:tuly: {
  sockwrite -n tuly GET $gettok($sock(tuly).mark,1,32) HTTP/1.1
  sockwrite -n tuly Host: $+($sock(tuly).addr,$str($crlf,2))
}
on *:sockread:tuly: {
  var %tuly | sockRead %tuly
  if ($regex(%tuly,/(http:\/\/.+)/)) { 
    $gettok($sock(tuly).mark,2-,32) $regml(1)
    sockclose tuly
  }
}

output is the same as the one you posted

Shortened URL: http://tuly.in/lYmBjY

you can also use the post method

on $*:text:/^@tuly\s(http\x3A\/\/w{3}\x2E\S+\x2E\S{2,3}?\S+)/iS:#:{  
  if ($sock(tuly)) sockclose tuly
  sockopen tuly tuly.in 80 
  sockmark tuly $regml(1) msg # Shortened URL:
}
on *:sockopen:tuly:{ 
  var %tuly $+(url=,$gettok($sock(tuly).mark,1,32),&submit=Shorten)
  sockwrite -n tuly POST /process.php HTTP/1.1 
  sockwrite -n tuly Host: $sock(tuly).addr 
  sockwrite -n tuly Content-Type: application/x-www-form-urlencoded 
  sockwrite -n tuly Content-Length: $len(%tuly) 
  sockwrite -n tuly $+($crlf,%tuly)
}
on *:sockread:tuly: { 
  var %tuly | sockread %tuly
  if ($regex(%tuly,/<.+value='(http.+?)'><\/h2>/)) { 
    $gettok($sock(tuly).mark,2-,32) $regml(1)
  }
}

the output looks like this

Shortened URL: http://tuly.in/lLwNaW