Ten days ago, all four members of Soundgarden sent a short email to their mailing list:

Thanks to all for signing up. Stay tuned for more details! Loudest of Love – Ben, Chris, Kim and Matt.

In other news about possible future news, Trent Reznor tweeted this yesterday:

1st official day of work in the studio.

Could this be for a Nine Inch Nails project, or another Trent-oriented work?  Only actual news will tell.