So here's what i'm attempting to do.

Setup projects (posts) to become only visible to loged in user. Classify projects by client (using groups in wordpress) Allow user to simply see the projects in the category.

In summary, I wish to me certain groups (of posts) visible to simply a particular user.

Does anybody are conscious of a great wordpress plugin that does that or a great way to do it?

Found a wordpress plugin that will it: Allow Groups http://wordpress.org/extend/plugins/allow-categories/