A few statistics from our database in early October 2008, from our version check script that sends a little (anonymous data to www.dokeos.com, as explained on the Dokeos admin page:
Total number of portals registered (some of them might be duplicates): 6 375
Total number of courses created on these portals: 122 054 (campus.dokeos.com accounts for 32 000)
Total number of users registered on these portals: 1 297 775 (campus.dokeos.com accounts for 210 000)
Around 5 000 downloads per month (sometimes a little bit more, sometimes a little bit less)
That's all I have at the moment.