From Sharepoint team blog the announcement of the release of the SP1 for WSS 3.0 and MOSS.
“I’m excited to announce the release of SP1 for WSS 3.0 and Office SharePoint Server 2007. Before you install the service pack there are some very important things to understand. In this post I’ll try to provide you with the resources you need to be successful in updating to the latest service pack. Please do NOT simply drop to the bottom and find the links and download and install directly on your production environments. It is essential that you understand the appropriate guidance and test out the patch in a separate test environment. For this purpose we have put together a special SP1 page on TechNet to guide you through the process. The more you know the better prepared you’ll be for updating your environment.”
You can find this announcement here.