There’s another mobile Moodle mod available and IT4ALL has it in place at their free professional development site (which runs the popular Moodle4Teachers program regularly). The Mobile Learning Engine (MLE) is a plug-in for Moodle which is available through SourceForge: http://mle.sourceforge.net/ and is for 1.9.x versions of Moodle only.
It’s a bit of a simpler approach and is not as flashy as the Moodle4iPhone web app that’s currently in testing, but it definitely gets the job done and could be a viable alternative to the Moodle4iPhone (especially since it’s currently available).
If you’re interested in seeing it in action checkout http://m.integrating-technology.com from any mobile with web access, or check out the official SourceForge page: http://mle.sourceforge.net/. Tons of more screen shots are available at http://mle.sourceforge.net/mlemoodle/index.php?lang=en&page=screenshots.php.
There are some great tutorials for installation and the plug-in seems very sound/end user-friendly. I was able to navigate through my profile and into courses using my Android-based phone. Overall, a stable and acceptable Moodle goes mobile plug-in.