This class is sometimes neglected (I'm one of this) but, with it, is possible to do some nice things.
For example, if you would like to set the timeout of a transaction (deprecated), the ServiceConfig class can be used as follow:
if (ContextUtil.IsInTransaction)
{
ServiceConfig config = new ServiceConfig();
config.TransactionTimeout += 1000;
ServiceDomain.Enter(config);
}
Nice :)