For all those who want to know the working of search engine robots they can get important information from a WebmasterWorld Forums thread as there is a discussion going on regarding the topic. Questions are there on the thread are:
What happens if my site forces a cookie?
How do robots interpret my page?
Do robots accept cookies?
The answers tell you that if your site forces a cookie the robot will not see anything if the page needs that cookie for robot to view the content. If you have any questions to ask or know answers to the questions, join the discussions.