There were no releases for over a year, not even minor bugfixes. Commits to the repository are infrequent and there have been no commits for last two months. Is it safe to start new project using this library?
There is a pretty fresh answer in their Google Group.
And here are current issues tagged as 3.1 candidates.
Guice 4 is now in beta (see https://github.com/google/guice)
Good news everyone!
Guice 4.0 released (https://github.com/google/guice/wiki/Guice40)
Guice is a largely feature-complete system. There are bugs, there are improvements that are in process, but the core is stable and has been for quite some time. That said, we've released 4.0-beta, so the new functionality, new constraints, new SPI additions are available for testing in the field. We should be releasing 4.0 final this quarter, or early next quarter depending on whether some internal things get in quickly or not.
来源：https://stackoverflow.com/questions/11859207/is-google-guice-active