There are quite a few keyboards out there for Starcraft 2 and previously that of Starcraft. The generally held view is that you wouldn't need anything special. If you look at all the Korean ProGamers they all use a pretty old bare bones keyboard made by Samsung when they were still in the business of making keyboards and they can be obtained at about $10. Although the days of $15 mini optical mouse use will still be gone due to the heavily increased resolutions. So the keyboard would be right beside their $50 to $100 mice. If you look closely at the pictures or videos of Korean players duking it out you'll notice another anomaly! Those white or black plastic-ey keyboard that they use; they are filled with gaping holes. That is right, they remove the keys most likely to interfere with play, leaving only the useful ones. This means taking out things like the Windows key, which can cost you out of the game if you go to the desktop during a critical moment. Not hitting the wrong key at the critical times is very important in big games. Some people even like to warm up their fingers right before a match to improve 'blood flow and blood circulation'.
Razer has a really good looking set of keyboard. Their special keyboard is called a Razer Marauder keyboard although it bears little resemblance to the real Starcraft 2 Marauder firebat replacement unit. It does however look pretty good in part due to the dull metallic finish that makes it look right in place in the Starcraft 2 universe as well as its APM sensor lighting system that shines a different color depending on your APM at that moment. This is very helpful if you want a constant visual guide of your performance during the game. Of course merely having a higher APM doesn't mean you'll be playing a better game. It is just that at the Diamond level the minimum APM one would see would be about 100+ going into the high 300s. If you're a person who's into improving APM, as well as having the budget for a $100 swanky keyboard, then you probably need not look further from the Razer Marauder (not the in game unit). Alternatively, Razer has some other line of keyboards similarly made for gamers just not specifically for Starcraft 2 but for other games too. They have things like programmable options and mini lcd screens and stuff like that if it is your thing.
If you use the Razer Marauder (Razer's gaming keyboard for starcraft 2) alongside their Razer Spectre (Razer's gaming mouse for starcraft 2), then you'll be enjoying a wonderful melee of flashing lights from yellow to red. This can make for quite a different play style since usually you'll be focused on the screen so the lights may be indicative that you need to up your game or alternatively might end up just distracting you which would be clearly not that great an outcome. In my humble opinion the Razer keyboard is probably currently the ultimate Starcraft Keyboard.
Steel Series also has a Z series modification for their proprietary line of keyboard (called the Zboard), which would have the hot keys helpfully highlighted for you. In my personal opinion this isn't really that great a thing as it requires their special keyboard so you can over load the special set of keys on top of it but if you already have it then why not. The dÃ©cor of the skinning just does not cut it for me. Steel series produces other wonderful products in the mouse pad category as well as gaming mice though. It can come in a bundle at about $50 at amazon, cheaper by about $20 from elsewhere. Or you can just get the minimal keyset at about $20 plus a bit. If I really wanted a keyboard that much and I had about $100 I would go for the razer marauder if only for the looks and funky lights.
As for me, when I'm out on the go I'll be using the keyboard on my mac book pro which works more or less fine I guess. It is a bit more cramped than using a separate (or regular) keyboard. For my desktop I use a pretty regular keyboard and it serves me well as the keys are easy enough to mash into the right key stroke orders without feeling like it was falling apart. The macbook pro's keyboard is a bit more stiffer and doesn't have quite the feel when you slam a key hard.
And this I felt when there I was playing Raynor's Party for the first time and a typing game pops out! It was practically the only game in the entire slew of Uther's party like mini games in which I had a comparative advantage and won every time it came out. It's a typical typing game which gives you a longer string of words to type and a lower time limit at each round. Sometimes it used dialogue between Zeratul and Jim Raynor, and other choice extracts from the game. The trick to this particular stage was accuracy, and though I could type much faster I slowed down so that the words would not smear into each other. Generally this kind of games requires a keyboard that you can mash into accurately instead of those that are more responsive but might result in you making more mistakes.
Ultimately whether you should shell out the cash for the new keyboard depends on how much you feel like spending money and less of what will really translate into performance. If you're reading this soon after this is written, you may consider getting one for yourself or for someone else as a Christmas present as it may make his/her or your day. That is of course provided that Starcraft 2 is a favorite game of the gift recipient. It does make a good Starcraft 2 Christmas Present nevertheless.