TechCrunch first spotted the removal of the application from Apple's stores.
Google’s last cache of an active page for the $2.99 iOS app was made on February 12, while the $9.99 Mac app was last seen on February 13, and the free Mac app Sparrow Lite was also last seen February 12. Right now, if you really want it, you can still download Sparrow for Mac directly from Sparrow’s own web site.
Since its acquisition of Sparrow, Google has launched a new email client called 'Inbox'. The app still requires an invite but it has received mainly positive reviews from those who've used it.
Notably, some of the former Sparrow team members were involved in the creation of Inbox, including product designer Jean-Marc Denis.