The SysReq, or System Request, key has an interesting history. Up until recently, it was a mainstay on IBM/Windows keyboards, generally tucked away on the Print Screen key, accessible via the alt modifier. Mac keyboards had no use for the key, and neither did Sun's; my venerable Sun Type 5 doesn't have it.
It's kind of obvious why Mac and Sun keyboards don't need it the moment you consider SysReq's history. The SysReq key was introduced by IBM in 1980, and was used to invoke low-level operating system commands in such a way that it wouldn't interfere with software currently running. Wikipedia is sparse on the key's history, but states that it traces its origins back to the operator interrupt key found on IBM 3270-type console keyboards for IBM System/370 mainframes. I'm sure someone in the audience today can provide a more detailed historical note on this one (I'm too young for this).
The SysReq key doesn't really serve a purpose for 99.9% of the computing audience today, although one common use will be familiar to Linux users: the Magic SysReq key. By pressing down Alt+SysReq and another key (which defines the command), you can issue low-level commands regardless of the system's state. This can be useful if your Linux system is experiencing problems. It only works if your kernel has been compiled with the
Lenovo has changed more than just the SysReq key. Function keys have been reduced to second-tier, so that you must press Fn+Fxx in order to invoke them. First-tier functions of the F keys are now things like volume and brightness controls. Lenovo also introduced the chiclet-style for keyboards, as has been in use on Apple laptops and many others for a while now.
You can pry my aluminium full-size wired Apple keyboard from my cold dead hands, so I can understand the affinity one can have for a keyboard. Since I know many of you would be willing to marry your ThinkPads, how do you all feel about these changes? And on a more general note - what other keys can we eliminate from keyboards?