The ground floor of our campus library is lined with public access computers, anyone can surf the Internet, search library database and access the scholarly journals in digital form. These machines run one version of Microsoft Windows operating system or other, anti-virus and security updates are non-existent. The only kind of maintenance these machines see is when they crash and someone runs a re-install with a Windows boot CD.
It doesn't take much to migrate some of these machines to gnu/Linux (if you can cut the red tap) and provide a secure and safe browsing experience to the users. There are quite some documentation that help you turn a KDE desktop or the popular Ubuntu Linux to work as a public access kiosk machine. Its relatively easy to setup and makes economic sense too.
However there are still some (technical) problems that need to be addressed, the needs of the kiosk mode desktop environment are quite different. Instant messenger clients running on a Internet kiosk need interface that enable users to log on without storing the user name, password to a user account on the computer. I haven't yet come across any exist free software IM clients that have this kind of facility. You can use the web based IM clients but they aren't a very good alternative.
Pidgin (formerly gaim) is the most popular instant messenger client that comes with most gnu/Linux distributions, it can connect to multiple IM protocols including AIM, MSN, Yahoo!, XMPP, ICQ, IRC, SILC, SIP/SIMPLE, Novell GroupWise, Lotus Sametime, Bonjour, Zephyr, MySpaceIM, Gadu-Gadu, QQ ,Google's Gtalk and more. However pidgin logon interface to aimed users with personal accounts. Perhaps this is one of the issues that free software IM developer should remedy in near future.