Yes, yes, I know this is a venerable U.S. expression, so hold your fire. Americans say things like “My fingers are crossed” or “Keep your fingers crossed,” to indicate a wish for good luck. The Brits like to use the phrase by itself, as Americans would say, “Good luck!”, or, similarly, to more or less mean, “Here’s hoping for…” An example is this headline from the local newspaper in the West Midlands town of Solihull: “Fingers Crossed for a Sunny Shirley Carnival.”
I have some sense that the expression is in the early stage of incipient NOOB-itude. I offer this from Andy Benoit’s New York Times preview of the NFL Dallas Cowboys: “The budding star receiver (fingers crossed on off-field matters) Dez Bryant is 23.”
And this quote from American Canadian director James Cameron, about the recent release of his most famous film on Blu-Ray: “We’ve been holding back Titanic. So, fingers crossed.”
notoneoffbritishisms.com 
Cameron is a Canadian.
Thanks, mate. Duly changed.
I’m American(NE) and say “Fingers crossed” leaving off the “keep your..” most of, if not, all the time.
Agreed. I’m an American and there’s nothing odd about saying “fingers crossed” as a standalone.
Fingers crossed for a Happy Mountain Day today at my alma mater. https://www.facebook.com/juniata
I think many Americans, myself included, would say “Cross your fingers” instead…
Do recall that crossing your fingers (usually behind your back) can also mean you are disavowing a promise. “Uh, you know that thing that I’m saying up front, there? Not really. Rotsa ruck, Engrishman!”
I’m sorry to have to report, Shirley Carnival was a washout!
Paul
Solihull UK
In India, we say, “I am crossing my fingers for you”! 😉
I’ve heard “Fingers crossed!” all my life (have lived in the southeast and northeast of America)