• As summarized by the chart above, interest in buying an iPhone 5 in the next three months jumped from 47.7% to 54.9% after it was introduced and has remained above 53% even as the launch craze faded and the Maps app emerged as an issue.
• Interest in Google (GOOG) Android phones fell in September (to 35.2% from 39%) but has since remained steady.
• Interest in Microsoft’s (MSFT) Windows Phone (currently at 6.5%) and Research in Motion’s (RIMM) BlackBerry (4.9%) trail far behind.

The chart below compares buying trends of the iPhone 5 with the iPhone 4S in the 2.5 months after launch based on an analysis of Tweets that contain the keyword “iPhone” and such purchase-related keywords as “bought,” “shipped,” “purchased,” etc. According to Munster, it shows the iPhone 5’s “demand index” up 30-40% year over year.

“More specifically,” he writes, “over the past two weeks, the demand index is up an average of 36% y/y  and we note that this is the iPhone 5 demand ahead of Christmas, when some may be waiting to be gifted the device, compared to the 4S, which would be in January given the 2.5 month comparison. Our 45 million unit estimate assumes 21% y/y growth in iPhone units, thus the demand survey gives us continued confidence in our 45 million unit estimate.”