British website CVG quotes an unnamed source claiming that Ubisoft are set to reveal sequels in both the Ghost Recon and Rainbow Six series later this year. The last Ghost Recon, Ghost Recon Advanced Warfighter 2, was released in March 2007 and it has been "sort of official" that we'd see the next Ghost Recon (Ghost Recon 4) released this year. The latest Rainbow Six, Rainbow Six: Vegas 2 was released in March last year, and it is probably more likely that we'll get a glimpse of the next Rainbow Six this year and a release next year.
It is of course likely that new iterations of Ghost Recon and Rainbow Six would headline Ubisoft's annual Ubidays event in Paris, but if the next Ghost Recon is indeed set to be released before the end of the year the announcement could come much sooner than that.