In February, two weeks after Apple (AAPL) unveiled the iPad, Flurry Analytics reported a sharp uptick in the number of developers installing its analytics tools in new apps for the iPhone — a device that shares the same operating system. (See The iPad that launched a thousand apps.)

On Monday the company took a look at February’s data and found that the pace of new development — “the single sharpest spike in Flurry history,” in its words — continued nearly unabated.

“Over six weeks since Apple announced the iPad,” writes Peter Farago, “Flurry continues to measure a significant increase in iPhone OS new application starts within its system. We continue to attribute this growth to excitement generated by the impending launch of iPad, now set for April 3 in the U.S. A large proportion of the applications we are seeing are custom version of existing applications tailored for the iPad.” (see here)

The chart above shows a 185% step-up in developer activity within Flurry since the iPad was announced on Jan. 27. For more Flurry Analytic charts, including one tracking the number of available apps at  Apple’s App Store vs. the Facebook platform, click here.

[Follow Philip Elmer-DeWitt on Twitter @philiped]