Didn’t think Twitter was mainstream?

All doubt about Twitter’s position in the media world was laid to rest this weekend as the company aired its first ever television commercial during the Pocono 400 NASCAR race.

The ad, which encouraged NASCAR fans to “see what he sees” (referring to a driver), was used to promote the special NASCAR hashtag page which Twitter created for NASCAR and announced last week. That page uses “a combination of algorithms and curation” to “surface the most interesting Tweets to bring you closer to all of the action happening around the track, from the garage to the victory lane.”

It’s an interesting and potentially lucrative model for the San Francisco-based company, particularly in light of the fact that Twitter and live television have a very good relationship.

But a television commercial? It’s an important milestone for the company, one that leaves little doubt Twitter is a mainstream media company — like it or not.

While hashtag pages may not be the internet’s replacement for AOL keywords (and Twitter probably hopes they won’t be given AOL’s fate), they could prove to be very important for the company, making them worth promoting prominently (read: on television). After all, two of Twitter’s biggest problems are the service’s signal-to-noise ratio and its ability to retain users.

In the case of the NASCAR hashtag page, Twitter is ‘curating’ tweets and photos that NASCAR fans would be most interested in, removing much of the noise, and it gives registered users who are racing fans a reason to come back. Incidentally, it also gives racing fans who aren’t registered on Twitter a way to interact with the Twitter service. Some of those unregistered users, of course, might opt to register to follow their favorite drivers after seeing that their tweets and photos contain content they won’t find anywhere else.

Because of the potential benefits, expect to see Twitter ink more media partnerships that bring the Twitter brand to a small screen near you during commercial breaks.