The first new feature will help those who tend to upload a lot of documents: Google has added the ability to upload folders, not just individual files. This upload will actually preserve the folder structure, which means that folders within folders will also be uploaded.
The second feature is a UI improvement, merging the upload feature directly into the documents list. This means that the upload settings have changed as well. The first time you use the new method, you'll be asked whether or not you want the files automatically converted to Google Docs and if you want images converted to text via OCR. When you add new files, a window will pop up to display the upload progress.
And finally, you'll be able to drag and drop directly into the documents list in order to start an upload. This will only work for individual files, not for full folders.
A couple things to note: many of these new features work on what Google calls "modern browsers" - Chrome, Firefox, and Safari. Also, you might find that as you upload more and more files to Google Docs that you run into storage limits. You can either delete files or pay for additional storage ($0.02 per GB per month).
Google says these new features will be available to users in the next month.