Adobe said Tuesday during its earnings call that it’s buying publicly held Utah-based Omniture for ~$1.8 billion cash.

It’s not your most instantly intuitive acquisition ever and it’s costing a pretty penny at that. Adobe didn’t explain to its own people where the web researcher fit.

Omniture, whose 5,000 clients include Disney, Apple, GM, Wal-Mart and Time Warner, is a web traffic analysis ISV and will apparently let the media folk and designers who use, say, Adobe’s Flash widgetry and its all-important but poorly selling, recession-hit Creative Suite see how effective their work is. It expects its addressable market to expand to marketing types.

It’s assumed there’s a cloud angle since Omniture has a SaaS platform that’s said to capture a trillion transactions a quarter as well as a recurring revenue model.

Omniture, which employs 1,200 people, is supposed to discern how much time a visitor spends on a web site, the number of pages visited and why he left, something we gotta see. An account’s ad mix can change because of the results.

Adobe will integrate the widgetry into its own software.

At $21.50 a share Adobe is paying a 25% premium, 45% if you look at Omniture over last month. There’s gonna be a tender offer.

The AP talked to Global Equities Research analyst Trip Chowdry who felt Adobe was overpaying by almost half for opearion, which has reportedly been losing market share to Google’s free analytics and lost $44.8 million last year on revenues of $295.6 million.

Adobe expects the purchase to be accretive to its non-GAAP fiscal 2010 results.

It means to create a new business unit out of the acquisition under Omniture CEO Josh James and said the deal should close by November.

Meanwhile, Adobe, whose shares fell on the news, said it made $136 million, 20 cents a share, in the August quarter, down 29% year-over-year, on revenues down 21% to $697.5 million. It’s forecasting earnings this quarter of 23 cents-29 cents on sales of $690 million-$740 million.