Announcing Service Pack 1 availability for Office 2010 and SharePoint 2010 has been made at the official blog of the Office Sustained Engineering and Release team
http://blogs.technet.com/b/office_sustained_engineering/archive/2011/06/28/announcing-office-2010-and-sharepoint-2010-service-pack-1-availability.aspx

More information about SP1 can be found here :

White paper for SharePoint Foundation 2010 (MSF2010) SP1   
http://technet.microsoft.com/en-us/library/hh301732.aspx

White paper for SharePoint Server 2010 (SPS2010) SP1   
http://technet.microsoft.com/library/hh285676(office.14).aspx

 List of all SharePoint 2010 and Office Server 2010 SP1 packages   
http://support.microsoft.com/kb/2510766

1 - 5 Common questions regarding the Service Pack
http://blogs.technet.com/b/office_sustained_engineering/archive/2011/07/06/office-2010-service-pack-1-5-common-questions-regarding-the-service-pack.aspx

SharePoint 2010 SP1 and the June Cumulative Update for SharePoint 2010
http://blogs.technet.com/b/office_sustained_engineering/archive/2011/06/29/sharepoint-2010-sp1-and-the-june-cumulative-update-for-sharepoint-2010.aspx