A new FPN added to Sec. 410.151 (B) in the 2008 NEC® eliminates the misconception that Sec. 220.43(B) limits the length of track lighting that you can apply to a branch circuit. Remember, this latter section is found in Part III of Article 220 (Feeder and Service Load Calculations), so the "150VA-per-2 ft.-rule" does not apply to a branch circuit.

The only conditions you must meet are that the connected load on the lighting track must not exceed the rating of the track, and a circuit whose rating exceeds that of the track cannot supply the track.