I can reproduce leaking objects with the juce demo plugin as well as with a Jucer built new audio plugin. Juce is the current tip, OS is Win7 64 bit and I use Visual Studio 2008 (Express). The build is 32 bit.
This should be related with the AudioProcessorEditor; it doesn’t occour if I don’t return a custom editor (return 0 in creatEditor() and return false in hasEditor).
I also get a C4373 warning about DerivedAudioProcessor::getOutputChannelName and DerivedAudioProcessor::getInputChannelName in PluginProcessor.h. The base class uses (int channelIndex) while the Jucer produces (const int channelIndex) as argument list.