Starting with the debut of Alan Greenspan's The Age of Turbulence in paperback, Penguin is offering an e-book in tandem with the paperback release.
Penguin is marketing them as "eSpecials."
As an example, the Greenspan e-book is based upon the original work's epilouge, and it's my understanding that this e-book will be periodically updated, to address future changes in our fluctuating economy.
Check out all the details over at Penguin's blog -- New "eSpecials" from Penguin Marks a First in eBook Publishing.
With our economy being what it is, looks like there may be a lot of "e-book specials" for Mr. Greenspan ....