Thoughts? It uses JSP, has a framework (API, module building capabilities, etc) but its considered a "portal server" which seems different from a application server product like NetDyanmics or BlueStone.
They call it a portal server because you can use their framework to build portal type sites that include things like personal pages (i.e. MyYahoo), custom and syndicated content, email, etc...
Epicentric runs on BEA Weblogic so it uses an application server to run its framework on but it is not an application server itself. It is only a framework you buy to help you build a specific type of web site.
Hope this helps.
It can run on any servlet engines that supports JSP 1.0.