Visit http://code.google.com/p/persiphi/ if your are addicted to Delphi 2010 or upper.

Edit: Dead link as the owner likely has renounced to opensource it. Nevertheless, his master thesis work in portugese (pt-br) is still available here. A good source of inspiration for those in search of sample using latest bleeding edge features of Delphi (Annotation, Rtti...) in the realm of object persistence.

UPDATE 1:

DevArt has released EntityDAC - An ORM for Delphi with LINQ support!

It works even with D11 (Delphi 2007).

UPDATE 2:

Marshmallow ORM framework by Linas Naginionis.

It has joined join the outstanding Spring4D project as a feature branch as announced here.

To keep abreast of the latest news head to the Marshmallow Google+ thriving Community page.

Dubbed MM ORM Framework by its author, it's a promising one.

Here you have one: http://code.google.com/p/delphiorm/