As McLaren were always at the forefront of racing technology McLaren could not be interesed in a piece of the electric racing pie. It was in a Reuters press relased on 05/09/2012, where Team Principal Martin Whitmarsh made pretty clear that Formula E series beginning in 2014 is not an indifference field for McLaren.
Thus, in November 13th it became widely known that McLaren will produce electric racing cars as part of a consortium chosen to work with organisers on a new world championship to be raced around city streets.
Spark Racing Technology is responsible for the production and assembly of electric cars, that will participate in Formula E and McLaren one of the major shareholders will provide electric engines, transmissions and electronics. Also, there are some unknown suppliers too.
This sounds very interesting, the only hesitation is whether the engines will be capable to cope with the conditions of a Formula 1 race and whether they will have the same characteristic sound of the engines as the electric motors are virtually silent.