I completed the upgrade to VS 2010 but with some warnings. Apparently nothing important.
[04/16/10,16:44:37] Microsoft Visual Studio 2010 Professional - ENU: [2] WARNING:Warning 1946.Property 'System.AppUserModel.ExcludeFromShowInNewInstall' for shortcut 'WinDiff.lnk' could not be set.
[04/16/10,16:44:37] Microsoft Visual Studio 2010 Professional - ENU: [2] WARNING:Warning 1946.Property 'System.AppUserModel.ExcludeFromShowInNewInstall' for shortcut 'OLE-COM Object Viewer.lnk' could not be set.
[04/16/10,16:44:38] Microsoft Visual Studio 2010 Professional - ENU: [2] WARNING:Warning 1946.Property 'System.AppUserModel.ExcludeFromShowInNewInstall' for shortcut 'Manifest Generation and Editing Tool.lnk' could not be set.
[04/16/10,16:44:38] Microsoft Visual Studio 2010 Professional - ENU: [2] WARNING:Warning 1946.Property 'System.AppUserModel.ExcludeFromShowInNewInstall' for shortcut 'Install Microsoft FXCop.lnk' could not be set.
***EndOfSession***
Here is my list: (I removed Visual Studio 2005 but not 2008)

UPDATE
Later today (4/17/2010) I noticed the following entries in the Application Event Log:
Error in Template (C:\Program Files\Microsoft Visual Studio 9.0\Common7\IDE\ItemTemplates\Web\VisualBasic\1033\AdoNetEntityDataModelVB_ASPNET.zip), file (ModelObjectItemVB_ASPNET.vstemplate). Invalid template element (TemplateID) value (Microsoft.Data.Entity.Design.VSTemplate.ModelObjectItemVB_ASPNET).
Error in Template (C:\Program Files\Microsoft Visual Studio 9.0\Common7\IDE\ItemTemplates\Web\CSharp\1033\AdoNetEntityDataModelCSharp_ASPNET.zip), file (ModelObjectItemCS_ASPNET.vstemplate). Invalid template element (TemplateID) value (Microsoft.Data.Entity.Design.VSTemplate.ModelObjectItemCS_ASPNET).
Error in Template (C:\Program Files\Microsoft Visual Studio 9.0\Common7\IDE\ItemTemplates\Web\VisualBasic\1033\AdoNetDataServiceVBWebsite.zip), file (WebDataService.vstemplate). Unknown attribute (_locID).
Error in Template (C:\Program Files\Microsoft Visual Studio 9.0\Common7\IDE\ItemTemplates\Web\VisualBasic\1033\AdoNetDataServiceVBWebsite.zip), file (WebDataService.vstemplate). Unknown attribute (_locID).
Error in Template (C:\Program Files\Microsoft Visual Studio 9.0\Common7\IDE\ItemTemplates\Web\CSharp\1033\AdoNetDataServiceCSharpWebsite.zip), file (WebDataService.vstemplate). Unknown attribute (_locID).
Error in Template (C:\Program Files\Microsoft Visual Studio 9.0\Common7\IDE\ItemTemplates\Web\CSharp\1033\AdoNetDataServiceCSharpWebsite.zip), file (WebDataService.vstemplate). Unknown attribute (_locID).
Error in Template (C:\Program Files\Microsoft Visual Studio 9.0\Common7\IDE\ItemTemplates\VisualBasic\Web\1033\AdoNetDataServiceVBWap.zip), file (WebDataService.vstemplate). Unknown attribute (_locID).
Error in Template (C:\Program Files\Microsoft Visual Studio 9.0\Common7\IDE\ItemTemplates\VisualBasic\Web\1033\AdoNetDataServiceVBWap.zip), file (WebDataService.vstemplate). Unknown attribute (_locID).
Error in Template (C:\Program Files\Microsoft Visual Studio 9.0\Common7\IDE\ItemTemplates\CSharp\Web\1033\AdoNetDataServiceCSharpWap.zip), file (WebDataService.vstemplate). Unknown attribute (_locID).
Error in Template (C:\Program Files\Microsoft Visual Studio 9.0\Common7\IDE\ItemTemplates\CSharp\Web\1033\AdoNetDataServiceCSharpWap.zip), file (WebDataService.vstemplate). Unknown attribute (_locID).
Although all these Item Templates where present, I ran "DevEnv.exe /installvstemplates" from an Administrator Visual Studio Command Prompt (2010) just in case.