Munq will not dispose anything. If you need this ability, it would be better to use a different IoC container, such as Autofac.
However, in many cases I doubt the real need for letting the container dispose objects for you. The unit of work is a good example, because your IUnitOfWork would have a Commit() method anyway, which is probably called in the application. The class that calls Commit is most likely responsible for the lifetime of the IUnitOfWork and therefore also for calling commit.
You can solve this by not injecting an IUnitOfWork, but injecting an IUnitOfWorkFactory. The class that needs a unit of work can than do the following:
using (IUnitOfWork unit = this.uowFactory.CreateNew())
{
// Do some useful stuff.
unit.Commit();
}
UPDATE Dec 2012:
My opinion about how to register Unit of Work instances has (partially) changed due to new insights and the way I design applications. Instead of injecting a factory, I currently like to inject an IUnitOfWork directly. This means that it would be good to dispose the unit of work when defined scope (such as a web request) ends. As @DaRKoN_ explained, since Munq 3.14 the RequestLifetime disposes instances.
This Stackoverflow question and answer gives a thorough explanation about when and how to inject unit of works directly, instead of injecting factories.