Berlin offers comprehensive public transportation in the for of underground (U-bahn) and surface (S-bahn) rail, tram lines and bus services. These are operated by the Berlin Transport Authority (BVG).
The Berlin public transport system is divided into 3 regions: A, B and C. For conference visitors a ticket covering zones A & B will likely to be fine. If you need to venture into zone C and extension ticket for each trip can be had for 1.50 EUR. This will be needed for example if you are arriving to or leaving from Schoenefeld airport which is in zone C.
Berlin Transport Authority (BVG) offers Journey Planner service on its website which you can see the details of the connection of your trip. Just type in the location of departure and destination (also could be an address). For the Journey Planner click here
Note: All tickets and passes must be validated before their first use. Also, taking a bicycle on public transportation incurs an additional charge.
This is the ticket that most attendees should get. A 7-day pass can be purchased for 27.20 EUR. This ticket has the added advantage that after 8pm on weekdays and all day on weekends an additional person can accompany you for free.
If your trip to Berlin is shorter then the whole week, you might also consider buying individual single-day-passes. These are available for 6.30 EUR each and are valid until 3am at the next day.
Berlin CityTourCard (up to 5-days)
This is a tourist-oriented ticket that, in addition to transportation, provides discounts to several popular tourist attractions. You can find more details here.
There are many bike rental shops in Berlin as well as rental service from hostels and hotels. Here is the list of some bike rental shops located near the location of Desktop Summit.
Note: Renting a bike requires you to show your ID and deposit.
Marble app for N900
Especially for the Desktop Summit, the Marble team has released the Marble Desktop Summit 2011 package which contains data for offline usage in Berlin for your N900. Find your way and explore Berlin during the Desktop Summit. Install the Marble Desktop Summit 2011 package to get offline OSM maps, offline routing and offline search data for Berlin in a single package.
More info here