Google+ has recently removed Interstitial page from its Mobile webpages. Other products like LinkedIn and Pinterest, still show these pages before you actually land on their mobile friendly page on Mobile devices.

According to me, Interstitials have their own importance. They inform the users about the native application which works better than mobile friendly webpage. I didn't care about that extra click to skip to the actual webpage. What about you?
Victoria A. Davis
Designing future webapps
I like webapps that take me to the Mobile friendly version directly. I hate to see Interstitials. There various other ways to promote native mobile apps.