I just designed multiple screens registration form in the iOS app. First we wanted to make it as single screen but then after little research I find out that it is much more comfortable for users when you split all informations in logical steps (2-3). It could be even more effective for the app developer. Let me explain.
When user come to the registration form which is too long, there is a big chance he will immediately close the app because he is frustrated about all that information which app wants. Also no one has time to deal with these long forms... In the mobile app there is another problem with space - when keyboard appears, it hides the bottom part of form and it can be easily overlooked. It is not very comfortable as well. Based on these arguments we splitted registration on the "necessary information" (email, password, name/surname) and the "optional information" (age, sex, country, etc.). This part can be skipped.
Another advantage is that very high percentage of users fill the first step of the form, so we have their emails, and when something happens in the second part we can contact them to ask whats wrong or to remind them they didnt finish a regisration.
Hope it helped. I'm curious about other opinions. :)