To get the Hauppauge MPEG-2 USB tuner running on the SheevaPlug, I grabbed the 'git' snapshot from the Marvell repository as described elsewhere here, took 'cbxbiker61's config file from the -rc8 version of his most excellent kernel series (renaming it .config and replacing the repository's .config file with it), then 'make menuconfig'ed it to add the necessary support as described on isely.net.
While watching "live" TV (actually recording to a local file on a USB drive attached to the 'plug with the tuner via USB 2.0 hub and simultaneously playing it back from a frontend on a different machine), after 5 minutes the load average hovers around 0.22, so I don't anticipate any major issues with usability as a backend.
I've passed the information along to cbxbiker61 so hopefully this will be included in the next generally-available kernel, but if you're in a position to configure your own kernel, the following additional modules are being incorporated when the device is plugged in:
Module Size Used by
s5h1411 9856 1
tda18271 34808 2
tda8290 13884 2
tuner 21036 1
cx25840 27716 1
pvrusb2 140728 0
dvb_core 88108 1 pvrusb2
cx2341x 13740 1 pvrusb2
v4l2_common 15096 4 tuner,cx25840,pvrusb2,cx2341x
videodev 34408 4 tuner,cx25840,pvrusb2,v4l2_common
v4l1_compat 16104 2 pvrusb2,videodev
tveeprom 11144 1 pvrusb2
I'm now able to do NTSC (analog) recording; haven't attempted digital yet (I have an antenna in my attic for ATSC, and there are a few clear-QAM channels on our cable service), but I plan to give that a shot after a "standard" kernel comes out with this support.