Ubuntuでは
~$ ffserver -f /etc/ffserver.conf &

~$ ffmpeg -f video4linux2 -s 320x240 -i /dev/video0 /tmp/test.ffm
FFmpeg version SVN-r0.5.1-4:0.5.1-1ubuntu1, Copyright (c) 2000-2009 Fabrice Bellard, et al.
  configuration: --extra-version=4:0.5.1-1ubuntu1 --prefix=/usr --enable-avfilter --enable-avfilter-lavf --enable-vdpau --enable-bzlib --enable-libgsm --enable-libschroedinger --enable-libspeex --enable-libtheora --enable-libvorbis --enable-pthreads --enable-zlib --disable-stripping --disable-vhook --enable-runtime-cpudetect --enable-gpl --enable-postproc --enable-swscale --enable-x11grab --enable-libdc1394 --enable-shared --disable-static
  libavutil     49.15. 0 / 49.15. 0
  libavcodec    52.20. 1 / 52.20. 1
  libavformat   52.31. 0 / 52.31. 0
  libavdevice   52. 1. 0 / 52. 1. 0
  libavfilter    0. 4. 0 /  0. 4. 0
  libswscale     0. 7. 1 /  0. 7. 1
  libpostproc   51. 2. 0 / 51. 2. 0
  built on Mar  4 2010 12:35:30, gcc: 4.4.3
[video4linux2 @ 0x840e2c0][3]Capabilities: 4000001
Input #0, video4linux2, from '/dev/video0':
  Duration: N/A, start: 1287287449.221094, bitrate: -2147483 kb/s
    Stream #0.0: Video: rawvideo, yuyv422, 320x240, -2147483 kb/s, 1000k tbr, 1000k tbn, 1000k tbc
Output #0, ffm, to '/tmp/test.ffm':
    Stream #0.0: Video: mpeg1video, yuv420p, 320x240, q=2-31, 200 kb/s, 90k tbn, 60 tbc
Stream mapping:
  Stream #0.0 -> #0.0
Press [q] to stop encoding
frame= 1056 fps= 63 q=18.7 size=     812kB time=17.58 bitrate= 378.3kbits/s   
と動くんですが

Debian 5  linux2.6.26では
ffmpeg -f video4linux2 -s 320x240 -i /dev/video0 /tmp/test.ffm
FFmpeg version r11872+debian_0.svn20080206-18+lenny1, Copyright (c) 2000-2008 Fabrice Bellard, et al.
  configuration: --enable-gpl --enable-libfaad --enable-pp --enable-swscaler --enable-x11grab --prefix=/usr --enable-libgsm --enable-libtheora --enable-libvorbis --enable-pthreads --disable-strip --enable-libdc1394 --disable-armv5te --disable-armv6 --disable-altivec --disable-vis --enable-shared --disable-static
  libavutil version: 49.6.0
  libavcodec version: 51.50.0
  libavformat version: 52.7.0
  libavdevice version: 52.0.0
  built on Jan 28 2010 20:57:25, gcc: 4.3.2
[video4linux2 @ 0xb771bec8]Missing/Wrong width, height or framerate
/dev/video0: Error while opening file
とのエラーで動きません

video4linux2が入ってないのかと思い
~$ svn checkout svn://svn.berlios.de/linux-uvc/linux-uvc/trunk linux-uvc
svn: No repository found in 'svn://svn.berlios.de/linux-uvc/linux-uvc/trunk'
とリポジットが不明みたい

いろいろ調べてみると
Linux 2.6.26 and newer includes the Linux UVC driver natively.
You will not need to download the driver sources manually unless
you want to test a newer version or help with development.
こんな記述もありました。

Debinaの件ですいませんが、
解決法を、ご存知ないでしょうか？