Isolated Ground Receptacles 2

Sure, but when IG circuits are specified, the specs almost always require the IG circuits not to have any other loads, and sometimes require them not to be in a raceway or cable with non-IG circuits.

From the NEC (2008. Sorry, my 2011 electronic copy isn't here yet):

"250.96 Bonding Other Enclosures.

(B) Isolated Grounding Circuits. Where installed for the reduction of
electrical noise (electromagnetic interference) on the grounding circuit,
an equipment enclosure supplied by a branch circuit shall be permitted to
be isolated from a raceway containing circuits supplying only that equipment ..."

Seems like that circuit must be dedicated to the isolated ground equipment. And another circuit can't share that raceway.

...shall be permitted to be...

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is NEC speak for a practice that may be desired under some circumstances by some people and it doesn't create sufficient risk to ban it outright. You are never required to do any of the "shall be permitted to be" items, but the inspector can't keep you from doing them either. Nothing says you can't replace all your non-IG receptacles in a whole building with IG receptacles, connect the one ground to both ground terminals and go along your merry way. Total waste of money, but certainly not prohibited.

an equipment enclosure supplied by a branch circuit shall be permitted to
be isolated from a raceway containing circuits supplying only that equipment ..."

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Consider an installation where a circuit leaves the panel in metallic raceway, transitions to PVC raceway buried in a slab and then rises up a wall and terminates in a metallic enclosure.
I would interpret this rule to allow the enclosure to be grounded by the IG conductor rather than pulling a second ground conductor through the PVC to ground the enclosure or outlet box..

Bill
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"Why not the best?"
Jimmy Carter

There's a slightly different case I found in the NEC (250.146 D). Aside from the "Isolated Grounding Circuit" provision which I previously cited, there is one for "Isolated Receptacles". The difference here is that an isolated receptacle is grounded by an "insulated equipment grounding conductor" which is permitted to pass through boxes, panelboards, wireways etc. with no connection to them or grounding bars. The NEC still requires boxes and wireways to be grounded, presumably by the usual means of metallic raceway and/or another grounding conductor back to the branch circuit panelboard grounding bar.

I don't see a restriction preventing this branch circuit from feeding both IG receptacles as well as those bonded to their enclosures and wireways. The 250.96 B restriction for "circuits supplying only that equipment" appears to apply when its the raceway/enclosure that is isolated.