One of the topmost customer requests has been for the datagrid. Unfortunately, we couldnt provide it for the V1 release. However, if this is a show stopper for you then you could use the xceed datagrid for WPF. It comes free and looks good from the demo.
"Xceed DataGrid for WPF is licensed for free, with an unlimited number of licenses per company, as long as each developer registers with their real name and valid email address at work. The free license is a perpetual license and includes royalty-free distribution, bugfixes, and new features, so your company can use it with full confidence. " - Xceed website
The xbap demo can be seen here