The challenge James, M1DST set for 2012 is: “Launch a high altitude meteorological balloon, reach inner space (approx 100,000ft), track it and then recover it. The payload must contain at least one camera but can contain as many cameras, experiments as it is deemed reasonable.”
A typical flight uses a standard latex weather balloon, lasts around 2-3 hours, and reaches 25 to 35 km in altitude.
There will be a talk by M1DST during the early part of 2012 to explain the project further. There are many world records in this area to be broken too!