Posting on its site, Technical Director Chris Kline wrote: “We're serious about making sure the PS3 version is great, and here's a little info on how we're going about doing it.
“We have no plans to hand off the PS3 version of BioShock Infinite to another studio. In fact, it's not a "port" at all. We have a much larger team than we did on the original BioShock, so we're doing simultaneous in-house development on the PS3, 360, and PC versions of the game.
“We all know that the PS3 is powerful but unique console with its own strengths and challenges. But compared to the PC, the Xbox 360 is challenging too. So instead of declaring a "lead platform" and porting the game to the others, we've instead changed the game engine so that all platforms look (to a programmer) more like a PS3. This means implementing a task-oriented task processor that assumes a NUMA (non-uniform memory access) design that mimics the PPU/SPU split of the PS3. Writing code this way is more difficult for us, but has a key advantage: it's both optimal for the PS3 *and* gives speed improvements on other platforms due to increased cache coherence and more efficient use of multiple processing units.
“All of our programmers have PS3 and 360 dev kits on their desks, and can test on the PS3 just as easily as on the 360. To make sure we find and fix problems as quickly as possible, we have a "continuous integration automated build system" that rebuilds the PS3 version and runs basic tests on it every time a programmer or artist makes a change to the game. It even emails them right away if they break something. In addition, we've also built tools that allow artists and designers to instantly check whether or not their levels will fit in memory on all three platforms, without ever leaving the editor"