How many people call that "a custom kernel"? Haven't heard anybody call an upstream distro kernel update a "custom kernel".
Is this a typical conversation people have?
"Hey Jim, did you update the servers to get the latest OpenSSL security fixes? - Yap, I compiled and installed a custom kernel".
Maybe they need to run a better distro with faster security update response?
That is what custom means in this context. "Not yours." Read accordingly; you've made the same flawed point at several spots in this thread.
I thought they used KVM for some reason... But I guess if they use Xen they yeah, they are stuck with whatever kernel they get.
It's no longer true that Xen needs to mean managing the kernel outside the VM. PVGRUB can be specified as the 'kernel' to boot, which will chainload a grub which can be managed inside the VM, which lets you run any kernel you wish and manage the boot process as you would on a non-virtualized system.
Amazon uses Xen for their EC2 product, and as I understand they too now set people up with pvgrub.