Spring together with Google are going to propose a JSR which will standardize/unify the injection principles in both frameworks:
"...We propose to specify annotations to enable the reuse of injectable classes across multiple dependency injection frameworks..."
The spec leads are Rod Johnson (SpringSource) and Bob Lee (Google). Bob is spec lead in JSR-299 as well, so it might help in the standardization process. It would be the best, if this JSR would even make into JDK. The DI approach is Guice-like and annotation based.
These are really good news. Hopefully the JSR gets accepted and makes as soon as possible into a standard.
NEW: Online Workhop Effective WebApps without Frameworks is also coming to: MUC Airport.