According to the latest NPD data and a note issued by Piper Jaffray analyst Gene Munster – reported by Business Insider – Mac sales for the first two months of Apple’s Q4 are up 22%, with Wall Street’s estimates averaging 16% growth for the entire quarter. Apple is expected to announce its Q4 results sometime in October, and back at the Q3 earnings call in July the company anticipated there would be a “future product transition” that would affect the September quarter – suggesting the next-generation iPhone would ship before the end of Q4.

As for the Mac, Munster indicates the release of OS X Lion, updated MacBook Airs and Mac minis on July 20 helped contributing to the 22% year-over-year growth in the same period; NPD data suggests Apple could sell between 4.4 and 4.6 million Macs in the quarter. In Q3, Apple sold 3.95 million Macs, and Tim Cook noted the MacBook Pros made up for the majority of Mac sales. It is no secret, however, that ever since the refresh in October 2010 the updated MacBook Air line has been growing in popularity among existing Mac users as well as new customers, with several analysts calling it Apple’s new crown jewel.

Meanwhile, Apple announced 1 million copies of Lion sold after 24 hours of availability, but hasn’t released new data since then. Apple has encouraged customers to upgrade to the new OS thanks to heavy promotion in the Mac App Store and by releasing a USB thumb drive for those unable to download the 4 GB OS installer. Lion also comes pre-installed on the new Macs released this summer, certainly another selling points for the Airs and minis.