I dont normally like to just post up stuff i find on others blogs ... but this is important :)

The WSS and MOSS bits are up on microsoft.com for download now.

MOSS: http://www.microsoft.com/downloads/details.aspx?FamilyID=2e6e5a9c-ebf6-4f7f-8467-f4de6bd6b831&DisplayLang=en
WSS: http://www.microsoft.com/downloads/details.aspx?FamilyID=d51730b5-48fc-4ca2-b454-8dc2caf93951&DisplayLang=en

Kudos to Angus & John Hodgson for these.

UPDATE:  Please read the following post for infomation on Installation instructions & Product Keys: Announcing the RTW of WSS and Office SharePoint Server 2007 Standard and Enterprise Evaluation!

UPDATE: Please note you will need to get a PID for MOSS.  Instructions for getting this will be posted on http://blogs.msdn.com/sharepoint shortly.