I’ve just installed the updates on all my test machines running Snow Leopard 10.6.5 before running it on my desktop where I’m still testing the MySQL 5.5 installation (using virtualized Mac’s, which is a big time saver). I’m very curious to what the app store might bring and I think you are as well. Therefore I’m happy to inform you that the Mac OS X 10.6.6. update does not introduce any problem for our setup. Even the Security content of the update won’t hurt us. So start running your “Software Update”.