Itanium processors, decreed Intel back in 1998, were the next big thing. The question was how to deal with the 32 bit to 64 bit data path transition, which had already been made by some high-end competitors like Sun and IBM. Itanium would be the high end, while consumers and small businesses could make due for another decade with 32 bit Intel based machines.
AMD (then Advanced Micro Devices) saw an opportunity and introduced x86 chips that could run either 32 bit or 64 bit software, or both. The idea was popular partly because it was far easier for software developers to upgrade x86 code from 32 to 64 bits than to create the new, Itanium code, which had a different instruction set.
Intel had to follow AMD's lead and introduce 64 bit, non-Itanium upgrades to its chips. In addition, the original Itaniums, introduced in 2001, were not very competitive with the IBM and Sun chips. Most businesses that wanted a 64 bit transition opted to go with the lower cost AMD or Intel chips.
Intel nevertheless continued to develop Itanium chips, with HP as their main partner. The market for them was miniscule. Software developers put little effort into Itanium. Red Hat dropped Itanium software development in 2009. Microsoft announced it would phase out Itanium in 2010.
Today Oracle announced it would no longer support Itanium. Oracle dominates enterprise business and database software stacks. At the high end, it now owns the former Sun franchise, and it also runs on the new SGI high-end computers, as well as the more everyday x86 chips from AMD and Intel.
That leaves Intel working with its original partner HP. They are both big companies, but they are drifting away from reaching critical mass with Itanium. Intel is likely to drop Itanium, which means HP will have to stick to commodity CPU chips or look for another partner, perhaps IBM.
The only significant winner I see from this inevitable death of Itanium is SGI. They once made machines based on Itanium, but their new supercomputers, the Altix UV series are popular because, while they run on standard CPUs, they are very effectively glued together by SGI technology. While SGI is a small company compared to HP and IBM, if they can catch even a modest percentage of the customers that need to replace aging Itanium-based computers, they will get a very significant boost. [note: I own SGI and AMD stock at the time this is written]
Intel Itanium processors