First I found that the new SDK complains about sockaddr not being defined enough to get addr family. I fixed this with (juce_mac_Network.mm:47) with a type cast (the temporary was there to get more readable error messages):
sockaddr_storage *sto = (sockaddr_storage*)cursor->ifa_addr;
if (sto->ss_family == AF_LINK)
I also had an issue trying to compile for iphone SDK 3.2.1 which was solved with:
$ cd /Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS3.1.2.sdk/usr/include/c++/4.2.1
$ sudo ln -s arm-apple-darwin9/ arm-apple-darwin10