When Sysomos published its initial “Inside Twitter” report last month that examined the people on Twitter and how they were using it, we discovered that 5% of users accounted for 75% of all activity. This was based on indexing 11.5 million accounts, and then looking at the top 5% users who accounted for most number of Tweets.

Not surprisingly, we wanted to learn more about this enthusiastic group. What we discovered is that 32% of all tweets made by the most active Twitter users were generated by machine bots that posted more than 150 tweets/day. The actual percentage of machine-generated tweets among the most active users is probably higher than 32% because there many bots that update less than 150 times/day.

Based on our previous “Inside Twitter” report and this “Most Active Users” report, 24% or one-quarter of all tweets overall, are generated by these very active bots. Many of these bots, however, are not spam, with some examples being @diggupdates, @deliciousrecent, @imdb, @twitseeker, @rosehose, @ladyreporter, @nieuwslijstnl, @dogbook, @ combatsi.

Among the things we discovered about the most active Twitter users are that:- Of the most active Twitter users updating more than 150 times/day, nearly all of them are bots operated by sources such as hotels offering deals, regional and national news services, regional weather services, the top news within Digg, games, anim services, tags within del.icio.us and financial aggregators. These very active bots account for one-quarter of all tweets.

Read the full report on most active users. Our main findings are:

- Among the most active Twitter users with more than 50,000 followers, we find singer Tyrese (@tyrese4real), actress Alyssa Milano (@alyssa_milano), celebrity Tila Tequila (@officialtila), TV host Jonathan Ross (@wossy), tech evangelist Guy Kawasaki (@guykawasaki) and blogger Robert Scoble (Scobleizer).

- 60.6% of the most active Twitter users live in the United States, while 6.9% are located in the U.K, 4.7% in Japan, and 4.3% in Canada.

- The split between genders among the most active Twitter users is fairly balanced with 54% male, 46% female.

- 88% of the most active Twitter users have never missed a day without making at least one update, while another 2.1% have only been inactive for one day.

- 48% of the most active users have more than 100 followers, compared with 6.3% for overall Twitter users.

- 44% of the most active uers more than 100 friends, compared with 7.5% overall.

- 33.7% of the most active Twitter users have joined Twitter this year, compared with 72.5% of overall Twitter users who have signed up this year.

ReadWriteWeb has a good analysis of the report.