Though this is great, some are having trouble getting it to work properly; here's a small step-by-step on fixing that issue.
Here's how to enable unzipping of .zip and .rar files in Chrome OS:
(works on the Beta and Developer channel)
1. Hit CTRL+ALT+T
2. From there, type in experimental_storage enable
3. Type exit and then you've got unzip enabled
Keep in mind that this is still a work in progress but nonetheless, it's making it easier for us to unzip .zip and .rar files on Chrome OS. The Archives folder is a read-only folder (not sure why) so it may make things difficult to adjust to at first.
UPDATE: While this feature is now working, two problems occur. Deleting a .zip file or .rar file is not yet possible when trying to do so through the Archives folder, however, deleting them from the File Shelf is possible as with any other file you download. You also cannot currently copy and paste to or from the Archives folder.