entrepreneurship requires different disciplines than manufacturing. Applying lean thinking to entrepreneurship requires a new definition of progress, one that is focused on measuring learning rather than measuring objects. The day-to-day process that startups build should also attempt to maximize speed of learning.
If it is on HBR then is it "mainstream"? I hope not, that would be sort of a tragedy. Not that I am against McKinMoney, Bane and other "strategic" consulting outfits get rich by coming out with a new methodology. I just hope there can be some real grass roots passion based entrepreneurship completed before "lean entrepreneurship" is turned into flow chart with 30 documents and 6 months of analysis.
If you want to dig more into this; read this succinct and very well written post by Scott Porad (http://goo.gl/KrZe). If you live in Austin, I would also highly encourage you to join the meetup group Ash Maurya has created (http://www.meetup.com/Austin-Lean-Startup-Circle/). Great group of people.