You don't have to waste time uploading files you haven't modified, nor do you have to manually create archives for multiple files. Once you've submitted a patch, you can check its status without bothering the project manager. Under Submissions, View my submissions lists all the submissions you've made on the project, including their current status. Check the ones you're interested in and you can get a detailed log of every action reviewers have taken on your submissions. Submissions can be diff'd with the baseline they were submitted against, so reviewers can easily see what changes were made.
Reviewers can accept or reject submissions and create folders for organizing submissions.
They never disappear and are always available with a couple of mouse clicks. In a strange case of humility, we didn't make a big splash about it. You can add a CVS repository to your project and give individual users access to read and write files in the repository. To do so requires the use of a CVS client, many of which are available for many different platforms. OAsis's new version control aims to make version control simple to use by doing everything over the Web.