While doing its financial thing this week, Ubisoft's said that Splinter Cell: Double Agent has been put back from March to September of this year.
"[T]he rescheduling to September 2006 of the launch of Tom Clancy's Splinter Cell Double Agent is meant to release the title on all platforms simultaneously, including the Microsoft Xbox 360 that should have a much larger installed base by that time," says Ubi's statement.
"This will also enable to maintain the highest quality for which Tom Clancy's Splinter Cell is recognized. This rescheduling will ensure the best return from the coming release as well as from future sequels of this brand over time."
Double Agent sees famously rugged spy-man Sam Fisher going undercover in an attempt to infiltrate a nasty terrorist group, a bit like Jack Bauer except with climbing on the ceiling. There's more info elsewhere on the site.
Also, it's worth pointing out that Splinter Cell: Double Agent's slip shouldn't effect the PSP version - Splinter Cell Essentials - which is due out between now and March.