Their website is still up: http://www.detachedsolutions.com/mirageos/

From the ticalc.org page, "Ranked as 2 on our all-time top downloads list with 1003409 downloads."

Over a million downloads over its lifetime, that's incredible. I never realized just how large the calculator homebrew scene was in its heyday.

Reading the title, I thought it was talking about the calculator shell too!