I just took my 2006 ZX4 SES in for an oil change today. I handed the service manager the article about the update / reflash whatever. They checked it out and found an update. Anyway, they updated the cars computer and placed a sticker under the hood with the update code. I asked the service manager if this update is the one that increases the MPG to match the 2007's and he said "Yes it is" Here is the code; I had the service manager write it down for me.
UPDATE 6U7A-12A650 BNA
If any of you use this code, make sure they check it out and make sure its the correct code for your Focus. I'm just going by what I was told by my local Ford dealer service manager.