The instructions say to download the translation pack into your install directory and unzip it. So, if, like me, you don't have access to the server that will allow you to unzip a folder on the server, logic says that you should be able to unzip the folder on your own machine and simply ftp the folder into place, right? Wrong. Well, at least sort of wrong.
Let's say you have the he-6.x-1.0 translation pack. You've unzipped it, and now it's sitting on your PC's desktop. You want to move it to your server. DO NOT copy that whole folder over to the server so that you end up with something like
/webroot/drupal/he-6.x-10on your server.
What you DO want to do is copy the CONTENTS of he-6.x-10 over onto the server so that the internal directory structures plop into place inside the existing directory structure in drupal. That way you will have something like
/webroot/drupal/modules/aggregator/translations/modules-aggregator.he.poand so forth.
As you can see here, each directory that has translations (modules, themes, etc. anything that has t() strings, really) gets it own translations directory and language po files go in there.
The easiest way to get all of those files to plonk into the right place is, in fact, to un-zip the file insitu at your server rather than trying to ftp the files over post-expansion.