The tablet PC has been around for years for Windows, but now there is a Mac version. This can be a very good thing for many Mac users that need this type of functionality.
What exactly is a tablet you may ask? The simple answer is that a tablet allows you to write on the screen. Why would anyone care about this? There are many reasons depending on how you work and what you want your laptop to do for you. The ability to write on the screen opens up a whole new world of opportunities to interact with your laptop. Take notes at meetings, use the pen as a mouse, perfect for doing work in a cramped space like a plane, drawing diagrams, signing documents, editing documents, and the list goes on.
We have several clients that use tablet style laptops since many of their employees edit documents on a regular basis. In the past they would print out the document, mark it up, scan the document into a PDF file to email to their administrative assistant to update, the AA would then print out the document and make the changes. Now they just mark up the Word document, save it, email it to their AA and they in turn make the edits on the fly. This often saves a lot of time and makes life easier for everyone involved.
I use an IBM/Lenovo Thinkpad convertible tablet which has the normal keyboard but allows me to swivel the screen and lay it flat so I can write on it like a thick piece of paper. This is great for meetings since there is no need to take notes on paper then transcribe them into digital later.
Mac Tablet info here http://www.axiotron.com/index.php?id=modbook and there may be an Apple version on the horizon.
Nearly all laptop manufacturers are making tablet style laptops so you can check out your vendor to see what they may offer. I expect more and more laptops on the market will incorporate the ability to write on the screen. Ultimately all laptops may have this functionality.
Now go out and write on your laptop! It could change the way you work.