The registration for 2011 BMW Berlin Marathon opened on Monday 10/18/2010. Berlin Marathon 2011 date will be on 25 September 2011. If you plan to enter and run at this premier marathon event hurry up because the registration is possible until 08.07.2011.
I expect the registration to close earlier than the deadline date because registration is first come first served. Another sweetener is that it will be cheap for the first 10,000 people at 60 euros.
For online registration go to BERLIN MARATHON REGISTRATION SITE. They also have an option of paper registration. You can download the PDF-File. Print it, fill it out and send it to the organizers by postal mail.
Another option for registering for 2011 Berlin Marathon is by buying a tour package organized by tour operators. Talk to your travel advisor.