Twitter sees annual growth skyrocket, while monthly visits flatten

Without question, the Internet phenomenon of 2009 is Twitter and Nielsen Online's usage numbers prove it.

Comparing unique visitors to Twitter's site in May of 2009 with May of last year shows a nearly 1,500 percent increase. Visits were up to 18.2 million, from 1.2 million a year ago. Time spent on Twitter also saw a dramatic increase, up 175 percent to 17 minutes and 21 seconds this May, from 6 minutes and 19 seconds last May.

Among those startling numbers, there's a dull one that shows time spent on the site by Twitter's users fell one percent in May, from April. Is this the beginning of the end for Twitter?