How meaningful is Twitter as a search engine? It may not have the market share of Google (65%) or Yahoo (20%), but it's starting to get noticed.

For the first time ever, Twitter was ranked by comScore's search rankings, accounting for .001% U.S. search market share.

Search volume on Twitter was 30.1 million, with 4.2 million searchers and 39.4 million result pages, exceeding the 22.2 million searched conducted on Time Warner Cable. As Mark Mahaney, analyst at Citigroup put it, Twitter is "becoming meaningful."

We were already starting to see hints of Twitter becoming the new shelf space, after Mark Cuban wrote this piece: Twitter and Facebook now compete with Google. In that piece, Cuban said: "For the 1st time ever, more people are finding my blog from Twitter and Facebook referrals than via Google.  The total number of people coming to my blog is increasing. The percentage of people who find it via Google is declining. Significantly."

Last July, when Twitter bought Surmize (the search engine that is now Twitter), I said after the acquisition that it was the start of Twitter ego searches, and potentially the start of a new business model - paid search. 

Today, it's unclear what the business model of Twitter or its search service is, but it's clear that it's another voyeuristic tool to search for who's talking about whom, and clearly a great driver of traffic to sites.