Take a look at what Amos Chapple was able to do by using Four Thirds and Micro Four Thirds cameras. In 2009 he won the Cathay Pacific Travel Photographer of the Year Award.
You can read an interview with Amos Chapple at http://blog.karimsahai.com/2011/03/the-photography-of-amos-chapple/. More pictures at http://www.amoschapple.com/.
As you can see wonderful work can be done with Micro Four Third cameras. Just a reminder: There are also two wonderful m43 stories at Craifmod:
1) The GF1 is a near perfect travel camera
2) Seeing prime: The Panasonic 14mm f/2.5 Lumix lens.
If you find nice professional works done with m43 and 43 cameras drop me a text at firstname.lastname@example.org! I will be very happy to post it here!