I work for a large local government organisation who are about to embark on using SharePoint to replace our ageing intranet with an all-singing all-dancing collaborative sit
My company has started testing Sharepoint Services (WSS 3.0) as it is a free version, it is short some features of MOSS (Sharepoint 2007) but it is free and comes with much of the things a company may require. However it is a Microsoft product so its always got some licensing 'gotchas'.
WSS has worked fine for us internally with document management, team collaboration, wiki / blog type functionality, it integrates with LDAP / Windows authentication (it is MS after all).