If you have a Silverlight 3 Beta 1 DataGrid that, for some reason, is not refreshing when its bound ItemsSource changes, like so...
<data:DataGrid ItemsSource="{Binding Path=Parameters}" AutoGenerateColumns="false" IsReadOnly="True" >
...you might want to know that it's a bug in the beta. I actually spent about 2 days on and off on this issue, researching a workaround and googling for it with no results. Only today, more on a guess than anything else, I did this:
<data:DataGrid ItemsSource="{Binding Path=Parameters, Mode=TwoWay}" AutoGenerateColumns="false" IsReadOnly="True" >
It's obviously stupid to have a readonly grid with TwoWay binding but, to my surprise, it started working ;)
Armed with this knowledge, I refined my google searches and voila, the following thread magically appeared. The link to the repro in the thread isn't working, but I assume it's about the problem at hand. So, anyway, just use TwoWay binding in the meantime ;)
update: I also noticed the same behavior for binding paths that go "deeper" in the bound object (e.g. "SelectedParameter.Value"), even if they are NOT used for the DataGrid (i.e. I have a case that's not working for a Button). Luckily, the same workaround works there too. The downside is that you have to be careful to not really use the TwoWay binding, thus inadvertently updating your ViewModel.