Micro-blogging service Twitter shut down for maintenance on Tuesday after delaying the move for a day because of its use as a communications tool by Iranians following their disputed election.

Twitter went down around 5:00 pm (2100 GMT), replacing its usual home page with a message saying “Twitter is currently down for maintenance. We expect to be back in about an hour. Thanks for your patience.”

The site also displayed a picture of a talking ice cream cone telling a caterpillar to “Hurry up.”

Twitter co-founder Biz Stone said in a blog post that the maintenance scheduled initially for Monday had been delayed because of “the role Twitter is currently playing as an important communication tool in Iran.”

A US State Department official said Tuesday that the department it had asked Twitter to delay the shutdown, but Stone did not mention any government request in explaining the decision to postpone the maintenance.

Protestors in Iran have been using Twitter for battle cries and to spread word about clashes with police and hardline supporters of President Mahmoud Ahmadinejad.

We expect downtime to be limited in the future or at least we hope.  This isn’t the first time Twitter was shut down for maintenance and we do suspect that it will be the last.