Update: Sony has gotten back with us regarding cross-game chat being implemented in a future update. The response is below.
Original: Cross Game Chat is not part of Sony's PlayStation Plus service and was never intended to be, apparently.
After the option was listed yesterday on several PS+ sites and then removed, we contacted Sony, only to be told by a rep that cross-game chat was not "part of the plan".
"Cross-game voice chat was not announced as part of PlayStation Plus," the rep told VG247. "The new offering provides subscribers features such as frequent discounts on PlayStation Store content, free and exclusive access to select games, full game trials, early invitations to select betas of popular games, and new functionality such as content downloads and updates which will automatically be "pushed" to the PS3 system even when consumers are not using their system."
We have contacted Sony to ask if Cross Game Chat is under consideration for release on future firmware.
A Sony rep has responded to our inquiry over whether or not cross-game chat was under consideration for release in the future:
"We do not comment on potential future announcements and while we have not made any specific plans to roll out additional PlayStation Plus offerings, we are always working on identifying new partnerships, developing new features and providing new content that our users want."
So there we go.