Piper Jaffray is out positive on Apple (NASDAQ:AAPL) raising estimates for September to EPS of $1.17 vs. Street at $1.11, and revenue of $8.37b vs. Street at $8.07b.

This quarter the iPhone will, for the first time, account for a meaningful percentage of booked revenue. Last quarter (June) it was 4%, and this quarter (Sept) they are modeling for it to be 21%. Given iPhone should account for 21% of booked revenue in this quarter, they are also publishing a metric that assumes the entire iPhone sale is accounted for in the quarter the phone is sold. Firm is calling this booked EPS and revenue. New booked EPS is $1.60 and booked revenue is $10.15b in the Sept. quarter.

How They Arrive At 2.8m Macs. Through the first two months of the Sept. quarter (July and Aug.), Mac NPD data is up 32% y/y. In the month of July, NPD data was 43% y/y and in Aug. units were up 23% y/y. However, they note that Aug. was a tough comp, as a redesigned iMac was released in Aug-07. But even if one assumes continued y/y growth of 23% in the month of Sept. (which they believe is conservative), the overall y/y growth rate for the full quarter would come in at 29%, implying 2.8m Macs in the Sept. quarter.

Piper's $250 price target is based on 27.4x (from 27x) CY09 booked EPS of $9.14.

Notablecalls: Note that JMP Securities was out with some cautious comments on the Macbook Pro demand. Just a fyi. No call here.