I have just completed a in-place upgrade from SharePoint 2007 to 2010 and everything completed successfully.
I have installed the Office WebApps and followed all the steps to enable Word, Excel and PowerPoint.
When I try an open a xlsx file form a Document List it returns this error message:
This workbook cannot be opened because it is not stored in an Excel Services Application trusted location.
To create an Excel Services Application trusted location, contact your system administrator.
I have checked the Trusted Location settings and the default is for the whole ShaprePoint server.
Opening Word docs work fine with the web version.