There are a lot of good answers here for simple methods to do a bit better, but I thought I'd add a couple ideas for getting closer to professional quality results.
Anytime you buy chocolate-coated truffles, they'll be coated in tempered chocolate. Tempering is a process of encouraging the formation of the "right" structure in chocolate that will give the final product a glossy shine and a crisp snap.
When you buy chocolate, it comes in tempered form. When you melt the chocolate, you usually lose the structure. The recipe you referenced tries to shortcut the process by encouraging you to barely melt the chocolate. This works, but it's difficult to do reliably. In order to keep your chocolate "in temper," it must stay below ~90 deg F. The alternative (and much more reliable) method is to completely melt the chocolate and then "seed" it to encourage the growth of the right kind of crystals. A good introduction can be found here:
Hand-dipping - The best you can do without (much) equipment
Picking the right chocolate
Commercially, truffles are either molded or enrobed. The easiest process to replicate at home in enrobing. In a chocolate shop, they use a big machine that pours a waterfall of tempered chocolate over pieces as they move along a conveyor belt. It's a really cool process, but not something you can do at home. Luckily, you can get pretty close with hand dipping.
You need to pick a chocolate with a lot of cocoa butter. When you buy chocolate commercially, you can choose among couvertures (the fancy name for chocolate) with different percents of cocoa butter. (And, if you're curious, retail outlets like Chocosphere make these available to regular people.)
In the store, your best bet is to look for blocks of chocolate aimed at baking. For example, Callebaut is a very well-known couverture maker and you can often find blocks of their chocolate in grocery stores:
The higher percentage of cocoa butter will have the effect of making the chocolate thinner when melted. This means it'll roll off the truffle and form a thin coating, rather than a thick one that will drip down as it dries.
The second trick, as others have mentioned is how you hold the piece as you dip it. You want to fully submerge the the piece of make sure every side has been exposed to chocolate, then you want to get as much of the chocolate as possible to fall back into the bowl before you place the chocolate on wax paper or Silpat to dry.
A fork is usually a better choice than a spoon because it will let more chocolate escape. A still better choice is a specialized dipping fork. They come in a lot of varieties:
Yes, people really use all of these for different shaped things they dip. My personal favorite for round truffles is the shape labelled 8 in this picture, but everyone has their own preferences.
With this technique, you can get results that look like this:
Note the small "foot" at the bottom. They look great, but, if a perfect sphere is your goal, they're not quite there yet.
Magnetic Molds and the Perfect Sphere
So how about the truffles you buy that are totally spherical with no foot at all? Those are made with magnetic polycarbonate chocolate molds. This is probably more work than you want to do. Don't bother with whatever molds you find in the local craft shop, the pros only use polycarbonate molds for a reason - they work. Silicone and other types of cheap plastics will frustrate you and not produce a glossy result.
Round molds are actually two part magnetic molds with a top and a bottom. They look like this:
With these molds, the shell (the outer coating of chocolate) is formed first and then the filling is piped inside. This requires a filling that's still liquid when it's piped. This is why you'll notice that chocolates like this almost always have a softer filling than those that look like the hand-dipped style.