I do not usually just re-point to older blogs, but some people including Don Smith were asking in the Persistence Ignorance session at Alt.NET Seattle about support for PI with LINQ To SQL.
I would maintain that LINQ To SQL supports a PI approach. I talked about it originally here but you might also want to read the relevant sections of my series on Architecting Applications with LINQ to SQL which cover mapping here and here.
The major lack is around support for a fine-grained object model i.e. you can’t map a value type to one or more columns only entities to tables. However, I don’t think that is a PI issue, but a modelling issue.