In other words, if you use the official Twitter app or Twitter.com, prepare for more ads to be inserted into your timeline.
Of course, there are still ways to avoid this. Third party Twitter clients don't have to show the ads (Not yet, at least. Who knows what the future holds.), so I encourage you to try one of those if you don't want ads distracting you. I recommend Tweetbot, although I hear Twitterrific is excellent as well.
On a side note, the introduction of ads on Twitter is one of the reasons many people have left it for App.net. You get what you pay for, after all. (Again, I'll be posting more on this later today.)