The problem is that OpenCL in OSX is ... not very good. I get the same error on a current DiabloMiner and any other GPU miners based on the phatk kernel. From what I see, the OSX OpenCL-compiler seems to optimize the entire kernel away, so it runs in zero time but zero results as well.

You can try the Mac app solution from this thread: http://forum.bitcoin.org/index.php?topic=8994.0

This is based on an earlier DiabloMiner with a non-phatk-Kernel, it works nicely for me, but won't give maximum hash rates compared to Windows or Linux mining.

So, you may either switch your OS for mining, or hope that the OpenCL in Lion will fix the issue...