Update: Gmail's iOS app went live tonight, but was later pulled due to a bug with notifications. It's likely to come back sometime tomorrow.

Google has started rolling out a revamped version of Gmail intended to make the webmail service as simple and streamlined as possible. Among the most noticeable changes is a redesigned conversation view that now shows a profile picture besides each sender, so it's easier to track who said what, and strips out as much as possible from messages so you can focus on the conversation.

The company also added a feature it calls "elastic density", which essentially means that the interface dynamically expands or contracts depending on the size of your Gmail window. If you prefer a denser view all the time, you can change your density manually in the Settings menu near the top right of the conversation window.

The navigation panel on the left now keeps labels and chat contacts in view at all times and let's users resize these elements to their liking. Meanwhile, searching has been improved with advanced search options available from a drop-down search window that appears upon clicking the search box. You can specify to/from fields, subject, word inclusion and exclusion, attachments, dates, and create filters right from the same search interface.

Lastly, themes have also been completely rebuilt for the new UI, carrying many of the old Gmail themes over to the new look while introducing several others based on high-resolution imagery from iStockphoto.

As usual, the rollout will happen gradually. Google says it'll bring the changes to everyone soon, but if you'd like to make the switch right away, there will be a "Switch to the new look" link in the bottom-right of Gmail over the next few days.

In related news, word on the street is that a Gmail app for iOS is waiting for approval on Apple's App Store. Currently, Gmail users on Apple devices have the option of accessing the service though its mobile web app, Apple's built-in Mail app, and a handful of third-party clients. While that may be enough for some, a native Gmail client could mean that iOS users would finally get such features as the color-coding that exists in Gmail for Android, improved search and filtering, the ability to zip through mulitple profiles, message prioritization, push notifications and more.