I cannot see a << operator for the Logger. Is one available? I prefer to use << for output. It is type-safe and extensible. The error/warning/information functions seem geared to ready assembled strings. I typically supply more contextual information. Using these functions I would have to assemble the string using an intermediate stringstream. This is inconvenient. A Logger could (maybe, perhaps) inherit from ostream which would allow more conventional C++ I/O to be used.
BTW, this criticism aside, I really like the look of the logger. It seems generally very well designed. I particularly like the asynchronous channel mechanism which allows one to log using a different thread.