There is not a "cumulative bundle" for ESX 3.x
We have a TOTALLY different mechanism of patching in ESX 3.0.x. vs. ESX 2.x
When we have a patch releases. There may be multiple of these ESX-xxxxxxx "patch bundles". Each "patch bundle" is independent of others, which means applying one does not include fixes from other "patch bundles". This gives customer the ability to pick and choose which "patch bundle(s)" the customer wants.
You can use esxupdate with the -n switch so you do not need to reboot between each patch bundle.
You can also set up a "Depot" to update multiple ESX Servers to ease the burden.
It's usually best to only apply patches that apply to your specific environment. It's not worth the risk to apply a patch for hardware/software you do not have.