The server is alive and kicking, but there hasn't been a release of Rebol proper for over a decade now. Red (https://www.red-lang.org) is an ongoing effort at a successor language.
That was about the last time I had even heard it mentioned. I still remember trying to play with it circa the early 2000s and thinking it had potential, but never coming up (at the time) with anything I wanted to solve with it.
I don't understand why developers go with these pronunciations. Clang is another offender. The obvious pronunciation was see-lang, but they went for clang, the word. That's insane.
That is not the pronunciation they encourage, read the whole line:
> It's similar to "rebel yell" or "rebel with a cause".
"Rebol" is definitely not meant to rhyme with "cause". The common word in the two is "rebel", the emphasis is on the way the syllables break and the sound of the first syllable, not on making it sound like "rebel yell" (which would be a bizarre way to pronounce "Rebol"). This is present to emphasize that while it looks like it could be made into "ree-bowl" or something, it's not supposed to be.