One of the big names in the espresso biz. Some years before Achille Gaggia managed to generate a brewing pressure of 9 bar with his spring-lever espresso machine, Illy Sr. was researching other methods to make high pressure espresso, including a method involving pressurized air.
Illy has been researching everything there is to know about coffee ever since the company was founded. Andrea Illy, with the assistance of Rinantonio Viani, wrote "Espresso Coffee: The Chemistry of Quality", one of the most comprehensive books on the subject of espresso. I can't speak from experience however, I've yet to read it.
They also roast coffee, which they have been doing since the company's beginning in 1933. Illy Caffe is specially blended and roasted for making espresso at home. It contains 100% arabica, which I find a little odd considering most Italian blends contain about 10% robusta for added crema and a little extra bite.
Aside from nearly 70 years of perfecting the blend, Illy Caffe stands out due to the companies packing method. As opposed to vacuum packing, fresh-roasted whole-bean coffee is packaged and flushed with CO2, keeping the beans from degassing, therefor holding in the flavor longer. Ground coffee is treated with nitrogen, also to prevent it from going stale.
Personally I feel the preservation method, while very effective, still cannot deliver the quality of coffee that's been freshly roasted (within a week of grinding), and freshly ground (within hours of brewing). But coffee fiends worldwide want Illy's unique blend. And since they roast in Trieste, getting coffee to mugs worldwide requires some amazing preservation on their part.