DD-WRT is the firmware for the most part although I'd bet there's some embedded code running below this Linux-based OS. Is there enough wiggle room "down there" to, say, surreptitiously forward inbound traffic between network segments and back (like a mini NAT)? I have no idea. Does anyone here know anything about the WRT54GL board?
The DD-WRT is just general purpose computer operating system that happens to be configured as a router which Linksys calls firmware to discourage you from tinkering with it. The ethernet and wireless devices, though, have more code, several thousands lines of it, running on slower, low power (but still complex) processors.
