UnitOfWork pattern?

I asked a question last night on the nhusers forum, and was immediately pushed into using this pattern. The funny thing is, they never cited a reason why, or how it solved my problem. Upon asking directly about it, the replies stopped (for now anyway).

Can somebody possible explain to me what advantage I’d have in using it? It would seem to me that the base repository class is already performing this role. The only real difference is that instead of each unit of work performing only one task, the repository supports several related tasks. They both maintain session based operations.

The really funny thing is, my question was whether or not there was a better way of refreshing the NH cache after a transaction, other than calling session.Clear right after the trans.Commit().