In addition to my blog http://marclenferna.com/blog/archive/2009/04/28/sharepoint-pre-upgrade-checker---can-you-upgrade-to-sharepoint-2010.aspx, check out the official SharePoint Team Blog description for the SharePoint Service Pack 2 release. I'm pleased to see there are slipstreams too for the folk who are going to install sharepoint for the first time with all its cumulative fix rollups.

http://blogs.msdn.com/sharepoint/archive/2009/04/28/announcing-service-pack-2-for-office-sharepoint-server-2007-and-windows-sharepoint-services-3-0.aspx