First of all, let me explode one common misconception.  Product positioning is not something you do once the product is built.

Product positioning isn’t meant to be kept a secret, nicely isolated from product development, sales and the rest of the company.  It’s not static either.

Product Positioning is not a Post-Processing Step
That’s the secret that Apple understands so well, and one of the reason’s why they were (albeit briefly) the world’s most valuable company.

Marketing does not begin once the product is finished and released.  Marketing is not just telling the world about your product – i.e. some product that already exists.  Marketing is an integral part of the development cycle.  It begins at product conception.  And it ends at product retirement.

Product Positioning: a "worst practice" at most software vendors.

Marketing is about:

• choosing what segments to sell to
• finding out what is important to those potential customers
• understanding the competitive landscape
• knowing what your competitive advantage is
• determing the price points that the market will support
• deciding what product to build

Product positioning, done well, encapsulates ALL of these points and more.  It helps drive development requirements, sales strategies, company strategy, support policies.  That’s why it’s so critical.

An excellent post by Tony Zingale, who knows a thing or two about successful software companies discusses this concept from a complementary point of view: the "go to market" strategy.

It’s also a lot of work.  But go ahead…ask Apple if it’s worth it.