I am disabled, I use a wheelchair, full-time, and was curious to know how accessible Berlin is concerning hotels, hostels, bed and breakfasts, and transportation. I am also considering trips to Great Britain as well, and Ireland.
I don't know about accomodation, but on transportation:
The Berlin U- and S-Bahn (urban rail) has elevators at larger stations, and level boarding from platform to train. If you look on the official map at www.bvg.de, stations with elevators are the ones with the yellow square showing a stick-man in a box.
The majority of buses are low-floor with wheelchair ramps. Trams may be a bit more difficult as there are still large numbers of high-floor trams, and even with low-floor trams not all stops have level boarding.
Philip, Berlin is fast replacing old trams without level boarding with new low-floor models.