[UPDATE] Amazon France has removed the Splinter Cell Trilogy page (the original trilogy's page for Windows exists, but not the PS3 page). The Prince of Persia page is still active.
[UPDATE 2] And just like that, the Prince of Persia page has disappeared. Gamescon is just around the corner, folks...
Yes, you are thinking correctly. There is evidence towards and HD compilation of the last-gen entries in Splinter Cell and Prince of Persia. This is two off my wanted list.
Entries on Amazon's French page point towards "Splinter Cell Trilogy" and "Prince of Persia Trilogy", both for 40 Euros (about $53 USD), both on November 2, and, the most surprising detail, both exclusive to the PS3.
That's not a typo, both are listed only for the PS3. Splinter Cell has been a multiplatform series up until Conviction, and Prince of Persia has never held any system preference prior. It, honestly, doesn't make sense to release a Splinter Cell HD Trilogy for the PS3 when the PS3 doesn't even have the newest entry (or, this could foreshadow a Conviction PS3 release). Unless Sony paid Ubisoft off, then there really is no need to limit these upconversions to one platform. Then again, each game would probably need it's own disc on the 360, increasing the cost of the game to Ubisoft, which defends the reasoning behind the PS3-exclusivity.
Bringing said entries to a system like the PS3 begins rumors of online multiplayer, but if the God of War and Sly Cooper Collections are anything to compare to, you're just looking at getting pretty graphics and a slew of Trophies. I do love me some Trophies.
I'm not complaining, I have a PS3, and I will buy these, whenever they come out for whichever system I damn well so choose. What I do see is that Sony could be banking on God of War Collection's success and the incredible interest in these HD ports of last-gen's biggest games and create their own line of said HD ports; a sub-brand of the PS3, if you will. By snagging exclusive rights to these collections would definitely secure Sony's interest in creating such a brand.
[Splinter Cell Trilogy at Amazon.fr, via Google Translate]
[Prince of Persia Trilogy at Amazon.fr, via Google Translate]