MG Siegler, blogging on his own parislemon site says multiple sources are telling him that the stars have finally aligned for a native Gmail iPhone app>
Perhaps the biggest issue with using Gmail through the iPhone’s native mail client is that Gmail is not Push-enabled. Yes, you can hack it to work through Exchange, but then you lose other functionality, such as the ability to star messages via flags. The native Gmail app will likely bring other key functionality as well: like Priority Inbox and one-click starring of messages. Other possibilities include some of the stuff Google is about to roll out for Gmail proper: like contact icons, better threading, and deep searching functionality. Maybe there will even be some Google+ integration, which Google is also hard at work on for Gmail.
While Google's Gmail has handy features, they've never made it play nicely enough with regular IMAP or Exchange mail to have Stars translate to Flags, and Labels to efficiently correlate the Folders. Because of this, Android has annoyed me for years by having separate mail apps for standard email and for Gmail. A real unified inbox across multiple accounts, Gmail and non-Gmail alike is compelling. For power Gmail users, however, a native iOS Gmail app is likely even more compelling.
Let's see how well Google can pull it off.