nod -- I appreciate you posting this link. I forgot about it. It seems to me the single greatest failure of acme, inferno, etc. is a lack of mainstream support. We have vim vs emacs today, but part of me always wonders about what the landscape would look like if acme was taken seriously by the programming community and actively maintained. It's too bad Limbo is so archaic.
Apparently Limbo wasn't too archaic for the Go guys--take a look at Limbo, then take a look at Go, and you'll find that the two are incredibly similar. Of course, if you consider the people who started Go in the first place, it's not that surprising!
I think one reason Acme never really took off was the same reason people go around using xterms with green text on a black background--sure, it's not especially easy to read, but by god it is haxxor l33t. Acme has about two keyboard combo commands (^a and ^e, to go to the start or end of a line) and expects you to select text, move frames, and set the insertion point with the mouse, and the mouse is definitely Not Cool, even if it means you have to hammer on C-n, C-p, C-f, C-b to get that cursor where you want it.
http://code.google.com/p/acme-sac/