Speculation in the Twitterverse has been rife as to what effect Oprah Winfrey's Twittering would have on the micro-blogging service's popularity, and now Hitwise has stepped in with some stats.

Twitter hardliners had been moaning that the influx of "soccer moms" would spell the end of Twitter's coolness, so it's interesting to see how many more people visited after the first lady of US TV plugged the service.

Share of US internet visits to Twitter increased 24% on Friday 17 April, the day of Oprah's first televised Tweet. Hitwise compares the visits with the previous Friday and visits were up 43%.

On 17 April, 37% of visits to Twitter.com were new visitors, 5% higher on Friday than the previous day and the average for March.

In addition, Hitwise reveals the search term "oprah twitter" was the 35th highest search term with the word "twitter" last week, something described as "impressive".