It is reported that the Metro Line #2 will connect the Pudong and Hongqiao airports by May 1, 2010, just in time for the Shanghai World Expo 2010.
Currently, the most effective transition between Shanghai Pudong Airport and Hongqiao Airport is still by bus or taxi. The Maglev is not a feasible approach yet, since it just arrives at Long Yang Road Station. You have to transit to Metro Line #2 first, and then transit to Airport shuttle at Jingan Temple Station, or taxi.
In 2010, with the east extension of Metro Line #2 to Pudong Airport, and the west extension to Hongqiao Airport, people can directly take Metro Line #2 to complete the transition. It is still not the fastest way. The pending Maglev, and event taxi or shuttle bus are faster than Metro, but the 1.5 hour is so much more reliable than other approaches.
So stay tuned, and wait… I will update as soon as Metro connects the two airports.