The Nissan G37 Convertible wasn't the only news to come out of the Nissan GT 2012 strategic plan. Apparently, Carlos the destroyer has gone on record committing Nissan to an all-electric vehicle available by the end of calender year 2010 which will compete directly with cars in its segment. This of course significantly raises the bar for green-tastic PR bragging rights and will leave the Chevy Volt and the plug-in Toyota Prius looking dirtier than a Flint River trout. Although Ghosn wouldn't commit to a price, segment, or volumes, he did say they were planning on having a regular lineup of EVs in place by 2012. Maybe that Denki Cube we saw in New York was more than just a concept car. [NYTimes]
NVH and temp isn't even an big issue for li-ion batteries since all that requires is a good enclosure and good temp control (not exactly really high tech stuff considering its just basically an air-conditioned aluminum box).
On the other hand, the cost and energy density of such batteries are more pressing problems that still haven't really been solved.
That said, most of the delays in EVs/PHEVs are on things unrelated to the battery, like the transmission in the Tesla and the redesigned accessories (air cond, wipers, sound system if I remember correctly) for the Volt.
Thing about Nissan is that it's Japanese and it's no secret the Japan government really supports EV development. The only affordable EVs from mainstream automobile makers are pretty much almost all japanese:
Mitsubishi iMIEV, Subaru R1e are examples.
Again 2010 seems to be "the year" for EVs/PHEVs. Hopefully at least a couple of these companies deliver to consumers in the US.