As you may know, Debian Jessie is the current stable release, while Debian Wheezy has reached the oldstable status.
Yesterday, the Debian Project has announced that both Debian 8.4 Jessie and Debian 7.10 Wheezy have been released, bringing package updates and security enhancements.
If you already have either Debian Wheezy or Debian Jessie on your system, you can get the latest upgrades by running the upgrade command:
$ sudo apt-get update
$ sudo apt-get dist-upgrade
The ISO images for Debian Jessie and Debian Wheezy have not been made available yet.