I preform all myy ESX installs from an http site using kickstart scripts and would like to know if it is possible to stip stream ESX? I've never tried it but my limited knowledge of Linux tells me it should be logical to simply over write older rpm files with the newer released patches prior to running the installation process.
Don't know if it is, but I'm not sure why you'd want to. VMware does release new ISOs every few months, eg 7/25/2008, 4/10/2008 and 1/10/2008 for ESX 3.5, so you'd only be slipstreaming in a few months of patches.
I deal with this be having the kickstart script call the esx-autoupdate script (http://www.vmprofessional.com/index.php?content=esx-autopatch), granted it adds time to the overall build process, but it works.