FREE is for me...and in this case, all you need to have done is purchased SQL Server 2000 at some time in order to download this handy tool for free.
Here is an overview of the Microsoft SQL Server 2000 Notification Services utility:
Microsoft SQL Server 2000 Notification Services provides organizations with a high-performance platform to build scalable notification applications that generate messages customized to meet their users' specific information requirements. The information updates users receive can originate from a variety of external sources, such as external data feeds and internal business systems, and can be delivered to various mobile devices, including cellular phones and Pocket PCs.
For a detailed overview from Microsoft, see the following link:
They have a page that describes the licensing as well:
And, finally, here is the download page:
Please shoot me a mail if you have had any exposure to this service and would like to share any feedback on it.