In terms of users, Madson and Claudia, we have this question asked on a regular basis. 
Sign Writing goes back to the early 1970s. At that point there was a newspaper in press type which was published in La Jolla and went out to libraries. The articles were in ASL, English, Danish, and Danish sign language. There was scattered interest in several countries, including Norway, and Spain, and Nicaragua. Pilot projects were started as soon as there was software to be published.
Trying to get a handle on "how many use SW every day" is very hard. For daily communication in the marketplace as a language of signage on the street, very few, but that may change in the next few years in Brazil because of pioneering work there among the Deaf. To graduate from the University of Santa Catarina as an interpreter one must know Sign Writing, so that is creating a small group of highly qualified signers (both Deaf and hearing) who use SignWriting every day in their own lives. 
Small school projects create pockets of school children in the U.S., Brazil, Nicaragua, Mexico, Columbia, and Ethiopia (to name a few), but we don't have day-to-day statistics on how many students from those classes continue to use SW as their everyday writing system once they are out of school and working with their own families. I'm looking forward to seeing protest signage in Brazil written in Brazilian Sign Language (LIBRAS). That, to me, would prove we have an independent Deaf culture expressing itself in its own language in the marketplace of printed word. 
We have researchers in more than 40 countries, but can say we have more than 20,000 people (a small town) using SW every day for commercial purposes. Not yet, but once one combines all the schools, all the teachers, all the users, one gets a distribution that is quite high, even if everyone is not fluent. 

Charles Butler
[log in to unmask]
Clear writing moves business forward.

From: Claudia S. Bianchini <[log in to unmask]>
To: [log in to unmask] 
Sent: Wednesday, February 8, 2012 11:48 AM
Subject: Re: Who we are?/ How many?

Helo Stefan,
Why I make you smile? Do I write something strange in english?

2012/2/8 Stefan Wöhrmann <[log in to unmask]>

“We have to work harder!!! :-)”
>Cannot stop laughing! ;-)
>Von:SignWriting List: Read and Write Sign Languages [mailto:[log in to unmask]] Im Auftrag von Claudia S. Bianchini
>Gesendet: Mittwoch, 8. Februar 2012 13:53
>An: [log in to unmask]
>Betreff: Re: Who we are?/ How many?
>I think it depends on what you think that using SW is! It's depend on the project (transcription, writing, education, translation, informatics?), the people involved, the cities involved...
>Can we tell Italians use SW? There is a group of italians using SW, but there are less than 10 persons (we just start spreading SW, after 10 years studing it for research purposes, so now we have about 50-60 persons knowing it, but did they use it? I don't know!). By the way, they use it massively to research purpose envolving writing and transcription. So we can't tel that Italians (all!!!) use SW, but we can tell that there is a "pole of excelence" on SW in Rome.
>I think that it very hard to speak about countries using it. I prefere to think that there are places where SW is used: Rome (10 persons), Toulouse (1 person), La Jolla (Valerie and the DAC's members)... Maybe in some palces it's more extended, because they use it at scool (but to be considered "spread" it have to be more than one single scool, I think). I hope that, frome those "pole of excelence" we can spread SW all around us, but it's not already done! We have to work harder!!! :-)
>2012/2/8 Madson Barreto <[log in to unmask]>
>Hello all,
>I followed the discussions in the forum and via email
>every day I see people of all countries participating.
>I have a question:
>Who we are (how many countries currently use the SignWriting)?
>Madson Barreto
>Claudia S. Bianchini
>PhD student
>Univ. Paris8 / UMR7023
>Univ. Studi Perugia / ISTC-CNR


Claudia S. Bianchini
PhD student
Univ. Paris8 / UMR7023
Univ. Studi Perugia / ISTC-CNR