I think we are going to start hearing about this soon. A guy got killed last year in Lake County because the steel was energized. I can't find any details but he was an appliance guy so I am guessing he was hooking up the dryer vent to an energized vent box in the wall.
Of course they are suing everyone in sight, including the LC building department.
I think an occasional metal box in each isolated section of framing, bonded to the framing would work but to be code compliant it would need to be bonded with a 250.66 conductor 250.104(C) attached with a nut and bolt (not sheet metal screw)

We've thrown this issue around a few times in our office and at the local IAEI meeting. The code clearly doesn't require bonding of non-structural metal not exposed.

The FPN note to 250.116 indicates the added safety that could come from bonding of the metal studding and framming in a building but we all know FPN's are not enforceable and noone will ever agree what "may become energized" constitutes.

I wrote a code proposal to bond metal studs for the 2008 NEC when I worked for Lake County. Also a code amendment for Florida was put in and already approved by the Electrical Tack Committee and on its way to the Building Commission for approval in May. If approved by the Building Commission it will be a change to the FBC and effective in November with all the glitch amendments.

I think this is possibly a good idea, except I can't figure out how it would be complied with?

Many of the homes I see built here have multiple metal sections not interconnected. Would each of these sections require bonding? And considering each stud is attached by means of a sheet metal screw, wouldn't also violate 250.8 for bonding of each component of a wall or section?

Too many questions on this ??????

Heres the story from "Local 6."

http://www.local6.com/money/7302637/detail.html

I think if we just required at least one metal box on the largest circuit in each isolated metal framing section, nut and bolt connected to the steel we would meet the objective of the code (the EGC of the circuit likely to energize...)
I think it is unreasonable to say this is "not exposed metal". As we saw in Clermont the dryer vent can is connected to the metal framing and exposed. The same is true of the medicine cabinet, also energized in that house. I can't think of a worse place to have energized metal.
You also have the possibility of metal door frames and window frames being energized. I think the reason we have not seen more of these incidents is we do usually end up bonding something attached to the framing somewhere, even if somewhat accidentally but it is not a certainty.
If you really enforced 250.104(C) you will end up with a 250.66 bonding jumper.
We have the "tombstone" necessary to get the government to act so I bet it happens.

Bryan, as for your "sheet metal screw" issue, the rule says the bonding jumper can't be installed with sheet metal screws, not that the entire assembly can't be put together with them. Screen cages have lots of joints held together with SM screws and we are happy to think they are bonded OK as long as we "through bolt" the lug.

Someone will probably invent a metal box that will clip to a metal stud and self-ground.

I do not agree! The use of sheet metal screws in 250.8 is as follows:
250.8 does not apply to using sheet metal screws to attach lugs to metal framing at screen rooms for pool bonding, or the connection of boxes to metal studs etc...

This was put into the code because some were using the sheet metal mounting screws on metal handy boxes, and 4" sq boxes, as well as wiring gutters, and panel enclosures to attach the grounding conductor, instead of using the threaded grounding hole and machine screw as required.

So can the metal box be attached to a metal stud with sheet metal screws? Yes!

Can a pool bonding lug be attached to the metal framing on a screen room with a sheet metal screw? Yes!

250.8 does not apply!

Lee County won't let you bond a screen cage with a self drilling screw. Maybe it is because it is called a "Pool Screen Enclosure" on the plan. ;-)