[baudolino]

This is a good idea, and one that I could certainly have used when learning Arabic— but its real utility is not for Modern Standard Arabic- it's for 'amiya/3amiya (spoken Arabic), which, to those not in the know, differs from region to region and is vastly different from both written and spoken forms of Modern Standard Arabic.

As someone suggested above, learning Arabic script is the first-- and smallest--of many challenges for those trying to learn formal Arabic.

There are few good systematized sources available for people trying to learn spoken Arabic, particularly if they're not particularly interested in reading the news or classical texts. I'm thinking of aid workers, diplomats, vagabonds, whatever.

A system such as this has great utility to these people— except it already exists in much of the Arabic-speaking world, particularly the Levant and Egypt, where numbers are used to represent sounds not found in the Latin alphabet.

For example: "You will speak Arabic soon" (Levantine) - "إنت رح تحكي عربي قريبا" - can also be rendered as "inta ra7 ti7ki 3rabi 2areeban". This makeshift system is used widely in texts in Lebanon and elsewhere. Utilizing this existing method will be easier and have wider applicability.