Hi,
Could you explain what the plugins do and what would happen if they were disabled?

For example
Mobile Joomla Plugin - This plugin must run first and is the main component. It recognises the browser using other plugins. It decides which template is required for a browser. If this is disabled then Mobile Joomla is turned off and will not work on the site.

Mobile - Simple - This plugin recognises common browsers from unique strings. This is to speed up recognition.

Mobile - TeraWURFL - This plugin uses a database of information about browsers and makes a subset of browsers that have visited the site. It first checks the subset, and then the main database to find information on rare browsers. If turned off then browsers may not be shown the correct template.

Mobile - Domains

Mobile - Always

Mobile - Domains - Choose corresponding markup for each of subdomain (the plugin may be disabled if site doesn't use "mobile" subdomains)

Mobile - Always - Allows to test site in mobile mode or to force site to work in selected mode only.

Thanks.
Joomla 1.5.22 MJ 0.9.11

Mobile - Always
I found the drop down parameters. It was set to Mobile Markup Auto (default)
so I tried the other settings. I had the user agent switcher in firefox turned off (default user agent)
xhtml-mp (WAP2/PDA) showed the site using the iphone template (URL www.joomlasite.com)
iphone (iPhone/iPod) showed the site using the xhtml pda template (URL www.joomlasite.com)
chtml (I-mode) showed the site using the imode template (URL www.joomlasite.com)
wml (WAP) showed the site using the wap template (URL www.joomlasite.com)

I tried it on another site too and the iphone/xhtml settings were wrong in the same way on that site too.

Mobile - Domains
As you described. I disabled the plugin and was unable to view the site in iphone template by using iphone.joomlasite.com or any other of the subdomain names. The plugin is working as designed.

There was bug in language file. Fixed about a month ago (will be released in 0.9.12).