Drupal 7.0 just hit the streets earlier today. This is the first time many people will face that the localization setup and update process is entirely changed (although it is not just changed for Drupal 7, also for older versions). Now translations are managed on localize.drupal.org, not as drupal.org projects, and localize.drupal.org generates its own translation distribution files for ftp.drupal.org, which are not included with drupal.org project releases (and are not going to be so). While this makes it easier to install Drupal 7 out of the box localized (you only need to copy one .po file instead of unpackaging multiple .po files in a funky structure), it makes it much more complicated to get and keep your contributed module localizations up to date on your websites.
Fortunately there is a great solution for this. Localization update module works similar to Drupal's built-in Update module in that it identifies the version of projects you are running with. But it uses that information to let you know if you have the latest version of translations for these projects, and downloads translation updates for you automatically. (It also supports custom modifications to community translation, and keeps track of those).
What's even better is that we have all built into one Drupal distribution now! The Localized Drupal distribution is built with Localization update module (as well as Localization client) to make all the automation around the new translation system available for you out of the box. I must say the easiest way to get started with Drupal 7.0 now if you'll localize your site right away is to go with Localized Drupal. It is still in beta for Drupal 7 due to the state of advancement of the two contributed modules bundled (which do need more testing and feedback), but in our testing, it works pretty well.
Don't miss the wave, get going with Drupal 7.0 today, localized out of the box! Please provide any issues you find in the issue queue for the distribution. Thanks!