Research firm Forrester released a report today titled "Microsoft's Shrinking Window For Tablets," saying the company "faces challenges in the tablet market due to its late entry."

Windows 8 tablets aren't expected on the market until sometime next year. (Rumored release dates have ranged anywhere from mid-to-late 2012 to even early 2013.)

Forrester analysts J.P. Gownder and Sarah Rotman Epps write that while Windows 8 looks promising for tablets, "consumer interest has plummeted during the past nine months. Windows product strategists will have to overcome several disadvantages associated with being a fifth mover in the tablet market."

Microsoft is placing a lot of hopes on Windows 8, which the company refers to as a complete reimagining of its flagship operating system. Windows 8 is being designed from the ground up to work on both traditional PCS -- desktops and laptops -- as well as touch-sensitive Web tablets. Though the company's Windows 7 is used on several slate tablets already, it's not optimized for touch, as Windows 8 is being designed to be.

Gownder, one of the analysts who drafted the Forrester report, wrote in Forbes, saying "Microsoft has missed the peak of consumer desire for a product they haven't yet released."

He points out that by the time Windows 8 tablets hit the market, other companies, including Apple and Samsung, will have "already launched second-generation products and will likely be into their third generation." And newer competitors like Amazon's Kindle Fire and Barnes & Noble's Nook Tablet driving downwards consumers' expectations of what tablets should cost.

"In Q1, 2011, Windows was by far the top choice of consumers - while no touch-first Windows tablets existed, 46% of U.S. consumers yearned for one," Gownder wrote. "By Q3, 2011, that picture had changed dramatically: Windows was no longer #1 in choice preference, and interest among consumers dropped to 25%."

(Photo of Windows 8 developer preview from Microsoft)