Using LLBLGen v2.6 (see full details in signature):

I have a class which contains a UnitOfWork. Multiple object may throw events that result in entities being added to the UnitOfWork to be inserted, updated, etc. Other events may trigger the current UnitOfWork being committed to the database.

Is there a way to determine if the current contents of the UnitOfWork have been committed to the database?

You can check the entities state in the internal queues. And you can get these Queues using functions like, GetInsertQueues() & GetUpdateQueues()... etc.

Another approach is to wrap the UoW in a custom class which manages a flag whether the UoW is dirty (Add.. methods have been called) or not (default status, or a Commit was called).

Commit returns the # of entities affected by the commit. If it's > 0, commit has ran. So you should simply use that value for determining whether it has ran already.