"In fact, EJB 3 does some DI (integration) standardization already. Why not Spring?"
If you annotations than Spring will be able to do the same thing.
"That is why Spring apps contain vendor-dependent integration code (and XML files)"
XML is unavoidable if you want to avoid hardcoding (but again Spring doesnt force you to use XML for DI, XML is just one popular way of doing DI in Spring).
The other alternative is to use annotations but again its kind of hardcoding since annotations are part of source code.
"Why not make Spring a standard in JCP -- so that all vendors can implement portable integration "toolkits"? Java has a strong tradition to standardize interactions between "components"."
Personally I donít see enough abstraction in Spring to be worth standardizing. I believe Sun thinks the same.