Aloe vera makes a gel which is useful for skin ailments. Eating the juice of true Aloe vera is, like Hamwild points out, a little confused. I guess you will find your bowels mobilized, but I don't think it's particularly healthy.
There are two plants which have historically gone under the name Aloe vera. The true species (yellow flowers, spotless adults) makes the gel that you can use for your skin. The other plant (now called Aloe officinalis) (usually orange/coral flowers, spots on the leaves of adults) works as a medicine you can eat. So there may be some confusion among older gardeners as to what the "true" Aloe vera is, and what are its properties. These are the two most common medicinal aloes in cultivation.
I strongly recommend against consuming any aloe that you cannot identify as a medicinal form. Many Aloe vera plants in cultivation are mislabeled, as people seem to think that any aloe is Aloe vera. I know this because I spent some time sorting out the plants in the database here under that entry. For the record, there are actually poisonous aloes, not that you would typically find them very often in cultivation, but something to bear in mind in a big-picture way.
There are other medicinal aloes. The most common (and most harvested for commercial production) is Aloe ferox, a big single-stemmed tree aloe from South Africa. I have also heard of Aloe arborescens used this way. In many places the people living in an area use whatever aloe they have locally as medicine, without discriminating too much, but this does not strike me as a good idea in the garden, especially when you have the choice to grow/find an aloe with the right properties.
