In order to start updating your Plurk/Twitter, you need to register first by signing in with your Twitter and/or Plurk account to Gladycast. Then you gonna be associating your mobile number to start Plurking/Tweeting via SMS. You can associate as many numbers as you want to your account.
The service is free. You only need to pay for the local SMS charges. So if you have free texts then that means it's totally free. Dang, how I wish they will have a Globe gateway soon because as of now they only have a Smart gateway.
Now if you’re a karma whore you won’t need to worry about having a karma down. As for me I really love it because I can update my status as soon as the story is happening and even when I’m away from a computer or even when the power is out or when there's no Internet connection available.
BTW, add me at Plurk and Twitter.