About Seam, we will use CDI instead, mostly because it's close to Seam concepts and because it's a JSR (JSR-299). We try to use standards as much as we can in Nuxeo.
We already have a code sample available on Github. It builds a nuxeo-cdi-distribution, which is a coreserver distribution customized to run CDI/JSF2 components in nuxeo-cdi-sample.
About Tomcat 7, the answer here is not as straightforward as the previous one. We'd be happy to do it, but it's not part of our priorities. So as Florent said, we'll start the work when it is a higher priority, and there is more demand for it. This might be accelerated if we have customer requests, but this is not yet the case.
I've chosen these two questions today because it's the perfect opportunity to tell you about the upcoming webinar I'll be doing with our CTO, Thierry Delprat. Simply entitled 'An Hour with the CTO and the Community Liaison of Nuxeo', we'll talk about some of the features that will be in the Nuxeo Platform version 5.6, and tell you a bit more about the roadmap and where we're heading technically. We want to make this as interactive as possible, so don't hesitate to come and ask your questions. If you cannot attend the webinar, feel free to ask questions in the comment section of this blog or on answers.nuxeo.com.