Clueful:
Adjective.
Possessing a
clue, or many
clues. The opposite of
clueless.
Clued-up.
Knowledgeable. Not needing any application of a
cluestick or
clue-by-four.
This word is a hacker's neologism, albeit a logically constructed one that has nothing directly to do with acronyms or algorithms, hardware or software. I'm a bit surprised that neither Webster 1913 nor the The New Hacker's Dictionary have written this up already. But for those of you who are not masters of the blindingly obvious, this is the brief definition.