Apparently there were a few glitches with the Linq samples in the Orcas March CTP. Erick has posted here about how to manually fix the Linq to Entities samples. You can also download all the updated samples here.
With some interesting exceptions (more on that in a separate post), it is safe to say that the design for the Linq technologies is being finalized for Orcas. This means what you see in the samples is probably fairly close to what will be in the final product. So if you have thought about checking out Linq but haven't for fear that Microsoft will change everything before RTM, this might be the right time.