HN user
When I was there, a variety of brands of hardware, mostly running RHEL. In fact running OS-X in datacenters was verboten, and eventually limited to a couple of small racks running on their own network segments where you could put in a mac pro if desperately needed to.
Fascinating to see an article about IS&T, definitely not something I ever expected to hear about on HN!
I was part of a team inside Apple that developed internal-facing tools for the retail teams. Our team was formed because of the extremely high cost in dollars and time that IS&T wanted to charge to develop some fairly straightforward tools. My team was taken from the departments that used the tools, and we developed things that were very custom-fit to what those departments needed.
Eventually politics overcame us, and IS&T finally managed to take over our team. We all became contractors in order to support the migration to their infrastructure, and continue development of the tools. A bit later we all became fired as our project was outsourced to contractors in India, managed by IS&T PMs who had no idea what our tool was used for and had never been inside a retail store. The tools all died shortly after that, some killed by IS&T, some petered out due to lack of use now that they no longer worked correctly or were a good fit for the users.
As far as we could tell, IS&T was run as a unique company inside Apple, which did it's fair share of price gouging in order to make itself money to keep going. Its purpose never appeared to be helping Apple customers or Apple employees, it was simply to get bigger, absorbing more money and power wherever possible, with no apparent reigning in from the parent org.
Although my experience is several years old, everything in this article rings true. The contracting companies they had us working for were taking a huge cut, the quality of the code they produced was dismal, (as soon as we were no longer allowed to re-write their code major things began breaking almost immediately) and people getting transferred around constantly and having no time to understand any one project was common. (rkho's comment about their hiring process seeming like it was simply a beard for a nepotistic contractor conversion was something we definitely saw a number of times.)
All in all it was an extremely eye-opening experience. Considering how "do it the Apple way" every other department we interacted with was, being in the IS&T buildings was like landing on an alien planet.