Arabic with Latin/English Letters

I've noticed in a number of bi-lingual blogs that there's an increasingly popular method for writing Arabic with Latin/English letters. For example: "AsSlamu 3alaikum ." I can usually figure out the system, but I came across a post recently that was in heavy Egyptian dialect and was using "2" and I just couldn't put it together. Can anyone post a comment with a translation of the lettering system or a link to one? For example 3 = ع and 7 = خ ? Right?

And, secondly, why are so many people using this system? It would seem to me that if you are a native Arabic speaker, you would be more comfortable typing Arabic with Arabic letters. Is it that people are learning how to type English in schools, or does it have something to do with phones and texting and all? Please post a comment to enlighten me.

Tagged by Dragon

I've been tagged by Undercover Dragon to post three sentences starting with sentence 5 of page 123 of the nearest book.

Here are my three sentences:

"It is laziness, our language is very lazy; we do not search for the names of things, we name them haphazardly and it is up to the listener to understand. The other has to know what you want to say in order to comprehend you; otherwise we are misunderstood.

This is the word I was searching for."

From "Bab al-Shams" by Elias Khoury. The speaker is talking about the Arabic language (the translation from the original Arabic is mine, but there's an English translation available from Humphrey Davies).