Konstantin Osipov of MySQL mentioned in his blog, that there is patch submitted, which allows using Query Cache simulateously with Prepared Statements. I believe a lot of us were waiting for this quite a long time.
This means, that we would be able to use native mysql’s prepared statements without speed penalty and switch off the emulation
Patch will be applied to 5.1 branch

jeah
Please do so
Important thingie it is