Update #2: According to their officialBlog, $ony has revealed that PS3 Firmware v1.82 is scheduled to be released soon. Due out within the next few days, this update will fully enable playback of AVC High Profile (H.264/MPEG-4) files.
Here is a new twist on the PS3 Network Hole... it can now be used to run PS3 .PKG files without Updating your Firmware to the 'required' version for each .PKG file. Props go to both NDT and CJPC for discovering this handy variation.
Take this .PKG TITLE and then grab an edited (to FW v1.00) PARAM.SFO file (or edit your own if you wish, grabbing one such as http://download-prod.online.scea.com/medius-patch/warhawk-pubeta/warhawk/20070608_r012/NPUA80093_113_PARAM.sfo from Warhawk) and then once again using a PC hex editor such as http://www.x-ways.net/winhex/ change the TITLE ID to match the .PKG file you wish to run and save it... in this case it's NPUB30006. Note: You can also change the TITLE field to a name of your choice (so that you don't have 10 'Warhawks' on your PS3 HDD) but this is NOT necessary so it's personal preference.
Now, following one of the previous PS3 Network Hole Guides note the following, a standard config file versus a FW Update Bypassed one:
1) The yellow PARAM.sfo represents your modified PARAM.sfo file (which can be named MyEdited.sfo or anything you wish) from above.
2) The addition of the bolded ../../../ which signifies going back (3) directories, and this is what makes this PS3 Network Hole variation work in order to bypass the .PKG Firmware Updates required when used in conjunction with your modified PARAM.sfo file.
3) The red NPUB30006 above represents the TITLE ID from your .PKG file... change this accordingly based on each .PKG file.
Currently this variation was only tested on Warhawk (which requires v1.70 to run), so you would only benefit in running v1.70+ .PKG files without updating from it using this method. More info will come as the resident PS3Devs experiment further of course- stay tuned!