1. Don't just launch an iPhone App, launch something for the iPad as well; for some reason Facebook still haven't gotten around to doing this so there's a gap here. A really well crafted Google+ experience for the iPad would make it stand out.
2. Company / Charity / Celebrity / Organisation / Fan Pages. Yep I know these are already on the way, I signed up for the trial here - http://goo.gl/zq95C. Let's see some differentiation from Facebook though; associating multiple employees, and letting them post to Google+ Company pages perhaps?
3. FriendFeed / Facebook style auto import of content from other social media sources. This is a difficult call as it could make Google+ into a noisy echo chamber. Sensible integration is the key here; an imported Foursquare checkin should check you in on Google+. Instagram photos should always go into a designated album. Bookmarks into +1's etc
4. Allow people to create their own, or submit their own content to, Sparks so they become more like #hashtags. Introduce community moderation to Sparks by letting users +1 or -1 content in a Spark stream.
5. Provide a browser bookmarklet, Chrome or Firefox extension to make it easy to +1 content out on the wider web (if the page owner doesn't already have +1 added to their site). Basically make sure +1 can act in the same way as 'Tweet This' and 'Like'. Supporting the sharing of Social Objects is the key to any social networks success, sharing a +1 is not yet as easy as Twitter and Facebook make it.
6. On that note, move +1'd sites into a users main Google+ activity stream. Again - networks are all about the Social Objects and +1 is Google's method for sharing. Why hide it away in a separate tab?
7. Push use of Circles across all Google products; I want the ability to share a Google Doc to all in my 'Colleagues' circle, share a Calendar Appointments to all in my 'Friends' circle or send a text message from my Android handset to all in my 'Family' circle. Circle integration throughout Google would be a killer feature.
Via Jon Mulholland.