As part of the Google+ redesign, there's more emphasis on what Vic Gundotra called "depth"--which means making it easier for a G+ user to move on from a single item of shared content to other, related items.
One way Google's doing this is by introducing automated hashtags. Leveraging its social graph data and analysis tools, Google+ will now automatically scan a post and add hashtags based on what it finds there. Users can remove suggested hashtags if they feel they're incorrect or inappropriate, but it's easy to see that if you're writing about the Eiffel Tower, an automatic hashtag like #EiffelTower is going to be handy--because it saves you the effort.
Interestingly Google+ will also scan images embedded in posts and add hashtags based on the content--which means if you include a picture of the Eiffel Tower you could end up with a relevant hashtag even if you don't write a word about it.
The hashtags link, like they do on other services like Twitter (and, possibly soon, Facebook), to related content that's being shared on G+. This is the "depth" that Gundotra mentioned--if you enjoyed something in a particular G+ update you now click on a tag and the new style panel will flip over and take you on to related content.
The idea is evidently user-friendly, but it's also in Google's favor because it may keep a user engaged in consuming G+ content for longer than they would have previously.
At Google I/O the company has updated its Google+ sign-in API with a powerful new feature that relates to new app installs and automated sign-ins. Essentially it requires that you're signed in to Google+ and are visiting a website. Now the site can now offer to install a mobile app on your device, and if you agree to this then you're automatically logged into it, once it downloads, via Google+.
The idea is to make it simpler and easier for users to access and become engaged with the content in apps, because it removes barriers to immediate use--those irritating demands that many apps thrust at you, insisting you select a username and password and so on, or go with your pre-existing Google+ ID.
Google's Gundotra noted that while Google's gotten very good at delivering lots of interesting content to its G+ users, they tend to be presented in a pretty inaccessible way--something like an endless newspaper that you have to scroll through. It's "flat," in other words.
Hence Google's redesigned G+ to present content in a sequence of different-sized panels. The result will be familiar to you because it's heavily reminiscent of Facebook's modern Timeline feed and even the way that Pinterest organizes its content. The columns vary from one to three columns based on what device you're accessing the feed from.
You can turn the features off and see G+ feeds in traditional single-column mode if you prefer, but the new panels are definitely a more eye-friendly way of organizing content.
Google has injected a little more power into G+ today by interweaving its Offers system with its social network. It's a pilot program and thus has a limited number of launch partners: Brands like Zagat, Hello Kitty, and Adafruit Industries--the maker movement and Arduino folk--are in the mix. The move means brands will be able to post special offers for their services to G+ and they'll show up in your feed if you follow the relevant brand.
This move is evidently a play to improve the advertising revenue earning potential of G+, but it's also quite subtle because it relies on social sharing: If one of the brand offers strikes you as particularly great, then potentially you could share it with G+ followers in your circle.
Google is also gently promoting the usefulness of G+ with this move. Many of the current crop of G+ changes have seen it become powerful as a back channel for data between apps rather than a traditional social network like Twitter, but the Offers move should appeal to users on this social level.