well he said gentoo, so i guess that means running gcc.

That is true right now. Making every integer and every pointer 64 bits is really a net loss performance-wise for most applications because it reduces the number of items that can be cached by 50%.

However, it is much easier to write server applications that assume all data can fit in virtual memory. All of my new server-side applications assume that the entire dataset of every process can fit in the virtual address space of the system. Effectively, my applications now require 64-bit machines to handle more than 2GB of data. This allows me to use mmap() and normal memory management (malloc, etc.) and rely on the operating system's VMM to swap for me. This is a vast simplification over trying to implement your own user-space VMM just to handle large files on small (32-bit) systems. I expect that the next generation of server software will all be design this way, and a lot of desktop software will probably adopt this kind of design too.