From The Verge:
Our sources also noted that Google isn't ruling out native Gmail clients for platforms beyond iOS and Android, and emphasized that Google wants to bring polish, "beauty," and ease of use to all of its Gmail experiences across platforms (a suggestion that a native client for Mac and PC might be in the offing). Sparrow, apparently, is a way to get there.
http://www.theverge.com/2012/7/20/3172365/sources-google-spa...