I am having the exact same problem, so I checked out the latest 2.4 stable from SVN and tried that. No luck :(
My server has the open_base_dir thingy enabled (with PHP 5.2.14), so that might be causing the problems here since the files are being placed in my silverstripe-cache folder, but they aren't being moved to the assets folder though.
What are the exact patches one have to make in order to fix this issue? I've seen a lot of patches but which one is the best?