We must first note that it would be very difficult to answer this in a definitive way. It is hard to determine how much globalization has occurred and it is hard to determine what impacts are due to globalization.
That said, globalization is likely to reduce global inequality but to increase it locally. Globally, we can see that some countries that were "have-nots" are getting much more wealthy because they are more able to trade with the rich world. China is perhaps the best example of this. This reduces global inequality. At the same time, inequality is growing in many countries. This happens as some people get much wealthier through globalization than was previously possible. Meanwhile, those who do not have skills that are usable in the global market do not become richer. This increases the level of inequality within the country.
Many people think it will reduce the global&domestic inequality but I don't think so. Globalization will increase it. Let's take a simple example: Greece. Greece was a rich country before it became part of the EU(european union). After this "europian-ization" the economy was ruined because of many factors. However other countries like Germany or France are now stronger then ever because of this union. So in conclusion Globalization will increase the inequality. The strongest places will become even stronger while the "weakest" will be their puppets and their economy will be worse.(specially the third world countries because they cannot handle such a big change). Hope this helps.