Thanks for the picture, WillJS.
I'm a little disturbed that the Help key has been replaced with "fn" on the new keyboard. I've always thought it very stupid that Windows computers didn't have a Help key and now for some reason, Macs have gotten rid of theirs. It doesn't make sense. Help is something used quite often, so it should have a dedicated key for it.
You have to look back quite a bit of time to understand this.
In August 1981, the IBM PC had 10 function keys to the left of the typewriter area. These were in the same places that certain keys were on the IBM 5250 and 3270 dumb terminals but instead of those specific functions, they were soft keys, useful for any purpose an application could want.
The first major application to offer help text was Lotus 1-2-3, which tied help to the <F1> key. Since that time, help text has been tied to the <F1> key in IBM's CUA and Microsoft's GUI documents. <F5> was refresh, <F10> was menu access, and <F12> was cancel.
Until the Macintosh II, there wasn't an extended keyboard that I remember. It was rather compact to match the machines with the 9 inch display. Since there weren't enough keys, there was no help key. When the extended keyboard followed IBM's new 101 key design that came with the PS/2, there was suddenly room.
Unfortunately, there is still no real standard for keyboards and when things diverged so recently, I suppose Apple decided that they should do what they wanted as well.