No, L1 cache will likely remain the same (it's important to keep the L1 cache small because you want latency to be very low for the closest cache).|
Here's the quote from ZDNet:
The new 750CX and 750CXe chips will be manufactured using IBM's 0.18-micron process with copper interconnects. They will also include 256KB of integrated L2 cache, a performance-enhancing technique, sources said.
While the chips should give Mac portables a performance boost, they will consume very little power, about 4 watts at 400MHz, sources said. The chips will also be inexpensive, with volume pricing expected to start at about $80.
Usually when you integrate L2 cache, a side effect is that you can reduce the package pin count because you no longer need the external cache out pins (makes the entire system cheaper to manufacture - cheaper packaging and no external SRAM cache).