These mentions line up pretty well with a series of reports claiming that the two series' are receiving HD remakes on the PS3. Ubisoft has already confirmed that the Prince of Persia trilogy is real, but will only be released in EMEA (Europe, Middle East and Australia) territories, later this week. Perhaps the company has changed its strategy (or has a different strategy for other regions), and is planning on a more widespread release over digital channels -- this would also explain why we haven't heard any hubbub about 360 versions of the two trilogies, as their respective download sizes would likely prevent them from slipping under the 2GB limit set for XBLA.
We've contacted Ubisoft for a comment on the references to the two releases.
Update: During the Ubisoft investor's conference call, CEO Yves Guillemot explained "We plan to come with more games for full digital distribution, on XBLA/PSN. Either with current games like Beyond Good & Evil, the first three Splinter Cells, and the Prince of Persia trilogy." Sure enough, an email accompanying the call lists The Sands of Time, Warrior Within and The Two Thrones as separate PSN releases coming sometime this quarter. No pricing, release date information, or any info about Splinter Cell was mentioned by Guillemot, nor included in said email.