should be able to zoom in/out to see all of the nodes being used / connected

Please please bump this up a priority level. Even on a high resolution monitor the screen if filled in seconds. It's not necessary to make new shaders, but good navigation makes work times faster.
PS. Consider adding bookmark jump to locations. And area blocks with commenting. The program is fantastic, but when a shader gets complex, some quick jump to points and some area blocks to organize and document would help a lot.
Example: Your leaf texture is fairly large. If there was block commenting, it could have the section that does the wind deformation labeled, and it would be easier for new viewers to understand. If I were in a production environment, I could hand that shader to another employee. They could jump to the wind section and tweak behavior with less deciphering.

Compound nodes would also solve the clutter very nicely... Actually these i would prefer if i would need to chose between zoom and compound nodes... still gave this my vote as on the long run it will be an important convinience feature!

Nested nodes has been suggested before too, feel free to vote on that as well :)

You managed to do it?! Awesome!!! :)

Good job man!

Yes, finally :)

Whoo hoo!