Irix appears to be on it's last legs. While it has not been end of lifed, and while new revisions come out regularly, these new revisions haven't had much in the way of significant changes for some time. And since the MIPS chips that this runs on won't be receiving any new updates past the current R16000s, it seems that Irix has a limited future.
Interesting/unique features of Irix:
My first Unix GUI was Openlook. Shortly there after, I got into linux, which felt more primitive until I got afterstep setup. Still, at that time I only had linux on a secondary 486/66 with 8megs, and a super crappy 14" monitor, so most of my interaction with linux was via telnet. I didn't go hard line linux on the desktop until 1998 when I was left having only that 486 (albeit with a lot more memory) as my only computer for 2 months. After that I just didn't feel any need to go back, so since then I only use Windows at work. Well, today I'm in the middle of putting together a dual boot windows/BeOs machine, but it will probably spend most of it's time in BeOs, unless I find myself playing a lot of games.
I was sysadmin for several Irix 5.2 boxen in Seattle for five months or so. I really like Irix. My favorite things were XFS and chkconfig. My least favorite things were that 5.2 doesn't have a decent development platform unless you spend buttloads of money on the dev packages. That meant that getting Tcl/Tk, Python, MySQL, etc. up and running was a nightmare. Each new version was just as much trouble. I am so looking forward to XFS on Linux. I found the Linux chkconfig on RedHat 5.1, but I haven't seen it on Debian. I hope SGI starts making PCI/AGP graphics cards that I can use in Linux.
What other ideas started with Irix?
-- ShaeErisson
Just thought I'd mention that the Irix 5.x devkit (IDO) is available for free online from SGI. I don't know how helpful that devkit would be for Irix 6.x boxes.
Also, SGI seems to be moving away from doing exceptional x86 machines. Their first line of NT machines had unbelievable hardware (unfortunately linux wasn't supported). However, their newest line is essentially a standard clone with an Nvidia video board and custom drivers. That's sad. Yes, Nvidia cards are nice, but they just aren't the same as having custom SGI hardware.
Just for the record, Linux was supported on their original NT machines... just not at the product launch. But if you look in any recent linux kernel, you'll see a configuration option CONFIG_VISWS. All the code for it was written by SGI engineers. They just didn't announce it at release time because they didn't want the Linux hype to take attention away from the badass-ness of their hardware. (That and the fact that it wasn't done yet). They even had their own RedHat-based distribution.
IndigoMagic? (the IRIX user interface, symbolized by the 4Dwm window manager) was pretty stunning in its day, even if it was just a significant remix of OsfMotif?.
At the time, SGI was trying to expand outside of 3D visualization, chasing a larger market for easy-to-use (ie non-geeky) graphical workstations (basically going after very high-end Mac users, such as printing houses). To that end it included the aforementioned interface, as well as a ton of built-in media (images, audio, and video) manipulation software and hardware.
Unfortunately for SGI that strategy never really paid off. It had some nice tech but, IMHO, much like Gnome and KDE today it was made by people who know the words to the Mac but not the music. Also, hardware commoditization was starting to happen in a big way.
Anyway, once WindowsNinetyFive arrived, the writing was on the wall. SGI killed its next-gen interface project and moved its interface team onto its Web-based admin project.
While the technology marched on (all the work on supercomputing), the desktop interface hasn't changed much in about 10 years.