Back in July, Google began testing a new look and feel for its excellent web-based email client, Gmail. And today, that new UI is live and available to all Gmail users. (I assume that in time it will simply become mandatory.) I'm still on the fence about the new UI, but Gmail remains the most productive and usable web-based email service out there.

gmail_2011_0

Gmail now sports the following new features:

Redesigned Conversation View. The Outlook-like Conversation View has been streamlined and completely redesigned and will include photo thumbnails for users in your contacts list.

Dynamic resizing and customizable density. As you resize the browser window, Gmail will automatically resize and adapt its layout to match the window size. Additionally, Google now offers three "display density" choices, Comfortable, Cozy, and Compact, which will help Gmail look better on displays of all sizes. (Compact is great for low-res screens, for example, whereas Comfortable might be a better choice for HD displays.)

New themes. I've never been a huge fan of Gmail themes personally, but the new themes in this release are high quality and available in HD so they'll work fine for any screen size. Some new photographic themes come from iStockPhoto.

Navigation changes. The left navigation panel is more customizable and finally lets you hide the Chat area (which I don't use) and resize certain areas.

Search improvements. A new dropdown in the Search box provides access to Advanced Search options that let you search email attributes like From, To, Subject, and via various criteria.

You can find out more about the new Gmail look and feel on the Google web site.

Additionally, Google briefly released a new Gmail app for iOS (iPhone, iPad, iPod touch) today but had to quickly pull it when a notifications bug was found. I've always found that Google's mobile web sites for Gmail, Google Calendar, Google Reader, and so on are quite nice, so I'm not sure what the point of this app is per se. I'll check it out when it's been re-released.