Twitter "house ads" appear

Yesterday Twitter put some new links on its web site. Some sites are calling them "house ads" and that got me to wondering about what constitutes an ad. The suspects in question link to Twitter features, either the new blog widgets or the twitter search engine. In the same way, the Twitter page is filled with links to our profiles, lists of followers, settings, etc. But these other links are just links, while the new links are being called 'house ads.'

So my question is, why are these considered ads? Because they have a border? Because they have a bit of explanatory text behind them? Or is it because each page load shows either the Widget link or the Search link (ie, they 'rotate')? Which of these aspects changes a harmless link into an evil ad? Or isn't it a quantifiable question? Do ads fall into the "something I know when I see it" category?

In the event that these are the precursors for paid advertising on the Twitter homepage, I can only see that as a good thing. If a small ad means that Twitter can keep growing and operating smoothly (it wasn't long ago that Twitter being up was more of an event than Twitter being down was) then I'm all for it. Of course talk is cheap for me; I use Tweetdeck.

So what about it? Is this the beginning of ads on the twitter page, or just a way for twitter to promote some of its features?

By the way, I put that Twitter widget on my personal blog and it works pretty well. I'm sure glad I noticed that ad link.

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