According to this they do! http://www.psu.com/Valve-confirms-PS3-PCMac-cross-platform-play-for-Portal-2--a010437-p0.php
That's certainly a change from the days when they were slagging off the PS3 and refusing to make any games for it
Valve’s beamed up a boatload of features for puzzler Portal 2 today, among which includes confirmation that the sequel will throw in cross-platform play between PlayStation 3 and PC/Mac owners.
In addition, the developer also confirmed, “persistent cloud-based storage PS3 saved games,” along with cross-platform chat for the aforementioned three systems.
Furthermore, Valve will offer a “Steam Play” of the title with every copy of the PS3 release, meaning a Steam key for the PC and Mac version will be featured.
“We made a promise to gamers at E3 that Portal 2 for the PlayStation 3 would be the best console version of the product,” commented Valve head honcho, Gabe Newell.
“Working together with Sony we have identified a set of features we believe are very compelling to gamers. We hope to expand upon the foundation being laid in Portal 2 with more Steam features and functionality in DLC and future content releases.”
Portal 2 hits shops for PS3, PC and 360 in North America on April 18. A PAL release will follow on April 22.
That's certainly a change from the days when they were slagging off the PS3 and refusing to make any games for it
