Hey guys,
Can someone update this with the proper steps/files? It seems that there is some incomplete information here and file links don't work anymore.
I would like to update my F500BT as well 
Actually, these steps still work; here's my upgrade path (having never added a single mod to my f500bt).
(Hint: Read the FAQs at the to of the hacks/mod section for some general knowledge/terminology)
(Hint #2: Step #5 - backup - is critical!)
1) Upgrade to pioneeer 2.006 software from the Pioneer site, via their instructions.
2) Grab the files from the FX3.1 update thread here: http://avic411.com/forum/viewtopic.php?f=34&t=32351. These are ALL the files you need for a basic update - nothing else required.
3) Extract the files from the RAR file to a freshly formatted 4GB SD disk. The RAR archive contains new files for the "My Flash Disk" folder on the f500bt. We're only going to deal with the APL2 folder on the f500bt and SD card.
4) Reboot f500bt with the 4GB disk inserted, letting the unit open in test mode (the RAR file contains not only the new files, but also the files required to start in testmode).
5) Copy/Move the APL2 folder FROM the f500BT to the SD drive in a safe spot (this is your "backup" - ie, put it in a folder that you've created on the SD card called "backup") - you can delete this folder from your device when done copying.
6) Copy the license file from your backup (APL2) to the "LICENSE" folder found under the My Flash Disk/APL2 folder in the SD Drive - you should know have 3 license files in the folder ( one generic, one pre-existing presumably linked to these new APL2 files, and your original).
7) Copy the entire SD/My Flash Disk/APL2 folder back over to the f500bt (into My Flash Disk/APL2), which restores the structure of folders to how it was originally.
Remove the SD card and reboot.
9) Drink beverage of choice.
You can actually do this same process by simply copying files from the APL2 folder on the SD card over top of the
files on the device and in theory it may all work (some others seem to have reported success). I had a hell of a time copying over though - certain files (ie, "EZRider") simply wouldn't copy properly, unless I copied it with a bunch of other files - no clue why, haven't experienced this with WinCE in the past (used to tinker back in the late 90s with WinCE).
In any event - single file download, a bit of careful copying and you're done. Should be doable in an 45 minutes or so (after the file download) if you work quickly and carefully, and happen to have an extra touchscreen stylus kicking around...