I just ran across this thread on TSS.NET. I found it somewhat curious that there is a Microsoft guy on there claiming that DLinq is not an ORM. While I don't doubt there's a way to construe the definition of ORM to make it not true (as the MS guys seems to try), I think that's counterproductive and just plain silly. As one of the commenters said, it looks and feels like an ORM, so why not just call it that?
At the MVP Summit, it was confirmed that LINQ will support extensibility into third-party tools via expression trees. The problem is first that they don't have that stuff documented and second that they plan to change it. This was gleaned in a session on DLinq where the product team was looking for feedback. They're very concerned about getting feedback, as Dinesh has illustrated, about DLinq, but I think that they need to first focus on getting their API for extending LINQ (a la expression tree structures and the like) solidified and documented ASAP.
On that note, I've talked to Paul Wilson here at the ASPInsiders Summit about DLinq and the aforementioned blog by Dinesh. Both of us have written ORMs, and both of us have commented on Dinesh's blog. However, you'll note, neither of our comments have shown up. I'm not sure what that's all about, but if you have feedback for the LINQ or DLinq team, you can post it on this post on dotNetTemplar, and I'll make sure that the related teams are aware of it. Now is the time to give your feedback on these products as they are early enough in the design cycle and are focused on that feedback.