PCIMCA is replaced by the express card. That is the way ahead and manufacturers are slowly rolling products out. There is no external memory slot either.
If your need is immediate, then your best bet is to get a USB-connected card reader. I have a multi-format adaptor made by SIIG and it works fine. If I recall correctly, it was on the order of $20 US. Probably ExpressCard devices are going to cost more than that when they do become available, at least at first.
I am not in a hurry since I actually own a 17" PowerBook with a PCMCIA card reader, which I use in a daily basis to transfer Excel files and JPEG files from SD cards and Memory Stick cards. My card is always inserted in my laptop and I don't need to worry about USB cables or readers. I am looking for something similar for my future 17" Macbook Pro.