During my brief stint at a POS provider, I was in charge of an OS/2 Warp system. This was last year, and the client using the system was a pretty major clothing retailer. never thought I'd have to learn Rexx in 2012.
I went to an undergraduates open day at IBM's Perth Development Lab. The exercises to try were in Rexx.
I think my first experience with programming was a Rexx app on an old Palm OS device back in elementary school. I made an interactive fiction game, if I remember correctly.