Six Apart on Monday announced an open-source plug-in for its Movable Type 4.0 blog software to help users of Apple's iPhone or iPod Touch with "moblogging," or mobile blogging.

The plug-in, called iMT, installs an alternate template set to make interacting with the MovableType application more efficient on an iPhone screen. It works over AT&T's Edge network or over Wi-Fi.

On Sunday, Six Apart said that it had made its TypePad hosted blogging service accessible using an iPhone. The company already offers access to users of Palm OS, Windows Mobile, and Symbian phones.

"Using TypePad on the iPhone is the best blogging experience for mobile devices thanks to its tap-based interface and custom integration with built-in iPhone functionality," said Six Apart in a blog post. "Blogs published through TypePad look great on the iPhone as well, thanks to our standards-based publishing engine and gorgeous designs."

While the iPhone may have an edge for interacting with Web-based blogging software, thanks to its full-featured Safari browser, many other portable devices are well-suited to mobile blogging.

Any portable device that can send e-mail or MMS can probably be used to publish content to online services that support non-browser-based submissions. Flickr accounts, for example, can be configured to publish photos submitted via e-mail.

A variety of companies offer mobile blogging services including Mdog, Mobblog.It, Nokia's Lifeblog, Photobucket, PixPulse, and Shozu, to name a few.

Competing services like Google's Blogger.com also support posting blog entries from mobile devices. And there are mobile blogging plug-ins available for WordPress, another popular blogging application.