Attribute to a user his own comments which were submitted when he was anonymous (not yet registered)

I need this for a review website. Sometimes people are lazy to or have other reasons no to register, but then some time later they like the site or again for some other reason decide to finally register. And if this happens all the products to which they already had given reviews being not registered become available again. And this is not desirable for a review web site. Not only review website, generally this problem makes the module pretty much useless for anonymous users.

And I believe to make it really excellent, the module should somehow attribute all the anonymous comments to their owners when they decide to register. Something like what http://drupal.org/project/sup module does - it creates a separate table in the database and creates pseudo users, associating anonymous comments with pseudo users through their session cookies (BTW, there is another great way: to associate anonymous comment with pseudo users via their e-mails - Drupal can be set so that anonymous users must leave their contacts, including e-mails) and after registration real users is created in .users table and all the data from pseudouser. table is just transferred to .users.

Would love to hear some elaboration of the module creator. Thanks!