Well, phone system hacking was traditionally called "phreaking" a few billion years ago.. much of that was the construction and use of "boxes" (dedicated circuits for the purpose) of various uses which were given names of colors... kind of a variation on the so-called "black box" concept. Clear, yellow, green, tan... all phreaking devices. Functions ran the gamut from DTMF encoding to payphone coin fakery. In many ways, Arduino is closest to Phreaking, as phreaking required the construction of physical devices to spoof electronic (and early computer) systems.
Cracking usually referred to removing software copy protection. This was most commonly done to games... though sometimes also to applications which a kid/hobbyist couldn't afford. Cracking required decompiling to assembler and reverse-engineering the code. Hard to do, but a dedicated kid with time on his hands, etc.. but did not require physical access outside of the floppy disk. Cracking is a form of Hacking, in the same way that phreaking is.
Hacking referred to gain access where one isn't supposed to be. Computer Hacking was just that- gaining (electronic) access to somewere where you aren't supposed to be. Usually requiring finesse, otherwise just plain old vandalism. Hacking is access - not about changing things or damaging them. Hackers (originally) did this for a sense of exploration, or to learn, or simply the Climbing Everest logic, "because it's there". Mostly, it was curiosity, nothing more sinister than that. Hacking definition grows thin when you are doing something someone else did before, and you are following what they did.. a memory upgrade KIT for your Atari might be owned by a hacker, but itself would not be a hack. If it's widely known and used, it's not a hack. Hackers felt a sort of geek elitism, so to speak, for having done things others had not. If however you hand-wired a rack of core that fell off a DEC truck to your Heathkit- that's one hell of a Hack. Like needing medication level.
Which bring us to our current hobby.. which isn't Hacking, really. These little buggers are meant to be messed with- they want us to diddle around in the guts of the beastie and are willing to help. If however you are mapping the output to an RFID fob for the purpose of spoofing an access-control door, that's Hacking.. with a little Phreaking tossed in. Most of what we do with Arduino would at best fit into the Phreaking realm. Making an infrared remote control transmitter to shut off all TV's in line of sight, a bit of a nice hack too. Hacking really is about being able to do something you aren't supposed to. Hacking can refer to using a device for something other than what is was intended for- for example, Wiichuck has to be called a hack, they never meant us to be able to use them outside of the Wii... but soon, as it becomes more widespread and documented, it will cease to be a hack. In that way, Arduino projects can qualify as Hacks, and us as Hackers, if the idea is innovative or obstrusuve enough into relatively "new" territory.
Just to say, that's what these used to mean back in the day.. there once was a great amount of pride in being called any of these terms, and for good reason. They all required a level of technical knowledge and ability to cobble stuff together that the general populace just don't have. I'd say most here have the capability of being hackers, it's a matter of inclination and/or a desirable enough reason to do it. It's not owning hammer that makes you a carpenter, so to speak. One other thing tends to be true- calling yourself any of these terms pretty much defined you as incapable of actually being said description of any merit. Since these are compliments, it's like walking around saying "Hi, I'm awesome and superior to others.." as a way to introduce yourself.
Assuming you agree with me, what would be the best term, in your mind?
Media pundits and fiction authors toss words about until they have lost their meaning, at least their truest interpretations..
A few props due because they haven't had any in a long time. Most of these guys are captains of the industry these days, nearly three decades later- for good reason.
[extra points if you can identify TECO and/or SAIL] [LOTS of extra points if you have either one on your computer.]