Positioning is one of the biggest challenges.  Naturally, it's the one thing in the organization that everyone thinks they can do better. 

Positioning in your market is a tough one. The biggest challenges are being different, appealing to existing needs, and positioning for the future.

They are all really tough and the subject of plenty of books.
 

Check out one of our recent blog entries.  Do you remember New Shimmer from an old (year 1) Saturday Night Live skit?

Positioning is not that tough, really.  The trick is to identify the frequency that your target market is tuned into and then broadcast on that frequency.  Ultimately your product's position relative to competitive alternatives will be determined by the market, not by what you say it is.