A correction from an earlier post on this blog: Visas are not required to make transfers in China within 24 hours of arriving, which is contrary to the information I posted a few weeks ago. I was misinformed then, and a very nice, smiling immigration officer at Beijing international airport informed me of this last week when I tried to use my Chinese visa to transfer from terminal 3 to terminal 2 where MIAT flights depart. Thanks a lot Chinese Embassy for the bad information...and taking $130 for the effort.
It turns out, however, that the new transfer system--that is, transferring from the new international terminal (terminal 3) to the old international terminal (terminal 2)--is not much different than before when one was transferring from a MIAT flight to a flight to the US. One still goes through the diplomat passports line and receives a temporary 24 hour visa stamp, and then exits immigration. Transfer to terminal 2 via bus, and then reenter customs and immigration to check-in at the MIAT counter. If all this takes less than 24 hours to do, then one does not need a visa to transfer in China.
As always, though, don't take my word for it. Check with your nearest consulate for up-to-date rules and regulations regarding transfers through China.