I too am interested in the answer.
the driving thread doesn't say much about pedals 
Guess I'll work on that then. Didn't think there was really much to say.
As far a the G27 goes, if working properly, the pedals work fine in MAME.
You may try reducing the joystick deadzone in mame.ini and adjusting the sensitivity in the "in-game" MAME menu.
Also try setting the pedals to separate in the windows control panel.
There is some other issue though if windows isn't recognizing it as a G27. You might try it without the pedals or shifter attached.
(if there is a problem with either, the G27 won't work, but if unplugged, the wheel will work fine without them)
...or it could just be that you don't have the proper driver installed.
All the analog pedal discussions seem pretty old - either from before mame supported them well or before there were many options in the marketplace.
Does anyone know of a mame compatible analog pedal that works well? (preferably usb to save on the hassle...)
I figure there must be PC pedals that work well enough...
What type of machine are they for?
Adding classic stand up Pole Position style to your existing cab?
Driving cab?
The only pedals I'm aware of being sold separately nowadays are high end racing $im pedals.
There are adapters available that will let you use the G25/G27 pedals as a separate USB device. You might be able to find a cheap set from someone who upgraded, but it's still going to get pricey.
http://www.sim-sport.net/index.php?page=shop.product_details&flypage=flypage_images.tpl&product_id=21&category_id=6&vmcchk=1&option=com_virtuemart&Itemid=10The cheapest plug and play route would be to buy a used PC wheel and pedal set, then hide the wheel.
If you want to add pedals to a stand up cab, I'd buy original arcade ones and wire them to an Ultimarc A-Pac.
The only standalone pedals that you might be able to find for a reasonable price are a used set of act labs pedals, but I haven't seen any in a while.