I've shot plenty of wedding cakes (all on location) and whilst the techniques vary I can offer some general advice on the location side of things to complement Stan's fine answer on lighting techniques.

Lighting wise I use a bounced hotshoe flash whenever there's a white or neutral ceiling. Otherwise it's ambient light. One way cakes are not like people is that they don't move about so a tripod/monopod can help in low light, allowing longer exposures. A good standard setup is to use the corner of a white ballroom and bounce the flash, and shoot from a lowish angle:

Sometimes this angle doesn't work, this cake is lost in the background and fails to pop:

I got closer and higher and shot the following which is a bit better (though I included both shots as the latter doesn't shot the whole cake). Getting higher can help obscure a busy background:

I tried the high angle recently when a plain background was unavailable:

But for this shot I ended up settling for a lower shot as it suited the cake. You need to experiment to find out the cake's best side :)

Sometimes the cake will be the centre of the room, this makes it very hard to get a good shot, this cake was far too high to get above without a ladder! It's handy to have a long/fast lens available to allow you to blur the background. This was shot at 135mm f/2.0, not perfect but better than it would be with the background sharp!

Here's another example of blurring a busy background:

Usually getting closer works (even if the background isn't quite as good, again an f/2.0 lens helps here):

Some cakes need some context, so be aware of that too!

Finally sometimes you just get lucky - this last one was shot with available light only!