Searching for some time for bulk edits of entities in microsoft dynamics crm, we couldn't find a way to do so. So, I went over creating a stand alone wpf application to edit the records of the crm.
After finishing the application, I discovered how to do that using CRM 2011!

Its by:
1) Exporting data to an excel sheet
2) checking a checkbox to enable re- importing of the data
3) editing the fields in a bulk way in the excel
4) re- import data to the crm

Enjoy :)