It really depends on what you're wanting to do. Monetizing is not just something you "do." It's more of a business decision that has to be planned out. I currently accept ads on my self-hosted site and have had some success in getting advertisers. But it's not something Wordpress does for you. You have to find the advertisers, pitch your site and post the ads yourself.
Lindsay is correct, it's not about monetizing Wordpress, it's your business that would be monetized. And that is very possible. You'll need to choose a niche which is what I have found is the best way to make more money. I truly don't think blogs with a ton of topics can be monetized as well as niche blogs/sites can. Figure out what your focus is going to be and start planning out your business. I personally don't have advertisers yet and do fine with affiliate marketing as far as monetizing goes.
Angie & Lindsay - blogs with many topics CAN be monetized. ANY website out there has the potential to be monetized, but it is based on how much traffic and if your visitors actually click on the ads. If they do not click, then you are not making money, no matter how many times a page with an ad has been seen.
You will make more as a self-hosted WordPress user as the opportunities to monetizing are vast: Pay to blog (Pay per Post or Social Spark), Adsense, Adbrite, Text Link Ads, Clickbank...etc.
When you place your Adsense, Adbrite, or Text Link Ads, you have to be strategic about it. Somewhere in your sidebar will not do for Adsense as you want to at least put 1 in your articles so the Adsense script will pick up your keywords and gear your ads relevant to your article.