Text Messaging

These days text messaging is getting more and more popular, especially with the younger generation. That being said, I have a client who may be interested in generating automatic text message go out to members. (indy Mogul does it, you just subscribe)
I am wondering if anyone knows how to go about doing this? Is there a special program needed, or a service that you have to subscribe to? What are the costs?
Also, chase bank is doing something similar where you can text them and they automatically text you back your account balance. Do you have any ideas how they are going about doing that?
Thanks

Here's a couple of services, at differing levels of customization and price.

http://www.mobilemarketing.net/
http://www.movomobile.com/
http://www.mozes.com/