As the current specification's rather generous 137GB is already starting to feel restricted, The Compact Flash association has unveiled the Compact Flash 5.0 specification which aught to keep us busy for a few years at least.
The first and foremost change, is the 48bit commands which allow for addressing as much as 144PB of data. To put that in perspective it's enough to store your, and your families entire lives in 3D HD video, enough to store the entire sum of written works by mankind in recorded history thrice over. Of course manufacturers are likely to start with more realistic capacities such as 1TB first, but it's nice see where things are headed.
Additionally the card will be compatible with current 28bit addressed CF cards, which will be able to use the lower 137GB of the card's capacity.
Other advantages of the 48bit commands is the improvement in speed. A single command can now transfer as much as 32MB opposed to the 128KB limit imposed by 28-bit commands. With this an image as large as 10MP could be written off in a single write operation!