Yes and no.
As far as FPGAs are concerned, I see no reason why you should not, technically, be able to handle a getwork on one of these and pass the work units to one or more FPGAs via USB.
These units do not, however, have a PCIe slot nor do they have any connectors which, to my knowledge, are capable of connecting to an external PCIe enclosure box, so GPU mining is out of the question.
The real problem you're likely to run into is software. The Raspberry Pi uses an ARM processor and runs on a custom-compiled version of Debian. All software running on the device will have to be compiled from source (since most projects don't just release ARM-compatible executables) and even then some software simply might not work. I'm not an FPGA expert by any means so I've got no idea what kind of software is required to speak to that particular hardware, but I do at least know that software is required and you'll probably have to do some tweaking to make that hardware work.
So yes, it's technically feasible, but don't expect it to be easy (or done for you).