A set of 3 converter cables have appeared, for connecting your NXT brick to RCX sensors, and Technic lamps and motors. Available to order in the UK for £6.99, not yet available to order in the US though.
Set number 8528:
Also a set of NXT cables. Though the details are confused. The picture shows the 7 cables, of three different lengths, from the NXT kit. The description says the set is 6 cables of 19.5" (50cm) length. Available to order in both the US ($9.99) and UK (£6.99).
Set number 8529: