The new version of Tweetie, the iPhone Twitter application acquired this month by Twitter Inc., says it contains a surprise. What's the surprise? When you pull down the stream of Tweets to refresh, a slot machine appears.

The slot machine's wheels spin, then stop. Some percentage of the time you're rewarded with a little graphic telling you that Tweetie will soon be known as Twitter for iPhone (congrats to you!). This sure looks like the future home of advertising on Twitter for iPhone, doesn't it? Twitter's Sean Garrett says that's not the case, "The slot machine thing is just a fun way to get the word out about the upcoming change from Tweetie to Twitter." It sure looks like prime real estate, though.

Now, there may not be ads up there in the future, but offers, promotions, paid inspirational haiku - something? That placement just seems too valuable for the company to let it sit there empty. Just as ads are coming to Twitter (relatively unobtrusive sponsored Tweets at the top of search results) so too can we imagine the free iPhone app will have ads. This seems like as good a place as any to put them. It's an easy assumption to make: tech investor Dave McClure freaked out on Twitter today calling them ad units, and the thought certainly crossed our minds when we saw them yesterday. Time will tell...

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