Just wondering what everyones thoughts on what ORM to use for SQL Azure?

I'm fairly comfortable using LINQ-to-SQL and I believe it is possible to get it working with SQL Azure. However, from my understanding (correct me if I'm wrong), no further improvements will be made to Linq-to-SQL in future releases of the .NET framework?

Alternatively, there is the entity framework... and further afield from the Microsoft Camp is NHibernate.

Ideally, any additional suggestions made should be free or open source. I have seen Telerik's ORM but this of course, is a commercial product.

I can get the definitions/benefits of each ORM myself by doing a Google search, but I was just interested in peoples opinions as to which ORM seems to work best for them (even if it is none of the above).