Any PHP tagging libraries extended for multiple object types?

Question

I have used freetag in other applications. (And I'm satisfied with it in those applications.) But like other tag libraries I have seen, it assumes a singular object type in the tagged objects table.

create table tagged_objects (
    tag_id int unsigned,
    object_id int unsigned
);

(This is not the table definition from freetag.)

I want to enable tagging for multiple object types in a new project - blog posts, forum threads, etc. In order to do so, I would need the tagged_objects table to be extended to include the object type:

create table tagged_objects (
    tag_id int unsigned,
    object_id int unsigned,
    object_type int unsigned
);

Are there any existing PHP libraries out there that extend the tagged objects table to include an object type?

Thanks