Conceptually, there is nothing really new, the differences are at a practical level.
What has really changed since these papers ('97, '98) is how the web applications are developped:
o the communication between the web and Java platform is now done by Servlets
o the API to use Transaction is standard (JTA) instead of proprietary
o Open Source software such as Tomcat and JOTM have commoditized and leveraged the use of these technologies
If you're interested by new ways to think the relation between web and transactions, you may consider some of the web services transactions specifications which are out (e.g. WS-CAF which was designed by Arjuna among others)