Proofing tools have come a long way in a short period of time.
I should point out that the use of multiple inks (6, 8, 10, and even 12 colors in some printers) is also designed to provide more even, accurate, and consistent ink lay down and to help eliminate problems like banding in gradients. The point, that increased color gamut is not always a good thing when it comes to creating proofs for the CMYK color space, is still an important one to consider.
Proofing by the numbers
Another important trend has been the addition of built-in spectrophotometers in inkjet proofing devices like the HP z2100 series (other companies also are rumored to be readying similar devices). In addition, all of the major makers of proofing devices have been working with calibration-device manufacturers like X-Rite to put together systems for making calibrating and profiling devices simpler, if not automatic.
The essential thought behind all of this is that producing an accurate proof is one thing, but having some way of verifying the accuracy of the output is an important part of communicating color. Print providers are replacing the traditional "sign off" on the proof with a digital signature indicating that the proof is within a specific range of accuracy.
What it means is we are no longer eyeballing the proof and injecting the rather subjective human input, but instead are reading proof data with objective, accurate and repeatable electronic devices. If the proof is off, the device will know it.
As in all aspects of proofing, there is a margin for error. The truth is, even the very best most accurate and most expensive devices for reading color will have some degree of variance. But these devices allow printers, buyers, and designers to agree up front what tolerances are acceptable, and to demonstrate objectively that the final proof is within those tolerances.
These "digital color spies" are also handy for keeping print devices calibrated and consistent, and the best part is, for many of these machines, the calibration process is automated.
Device link software and G7 color proofs
Software and workflow tools that support device-link profiles allow finer control over color conversions-especially CMYK-to-CMYK transformations. This can be used for color conversion, total area coverage control, and reducing ink costs by replacing CMY ink with cheaper black ink.