I've looked at the rootfs image and apart from /var/lib/dpkg/ changes (pretty much irrelevant) and new dates on /etc/gconf/ files there aren't that many changes. The list (the above excluded) follows below:

./etc/apt/sources.list
./etc/apt/trustdb.gpg
./etc/apt/trusted.gpg
./etc/apt/secring.gpg
./etc/ppp/peers/provider
./etc/ppp/pap-secrets
./etc/ppp/chap-secrets
./etc/group
./etc/hosts
./etc/pango/pango.modules
./etc/osso_software_version
./etc/chatscripts/provider
./etc/sudoers
./etc/osso-af-init/locale.orig
./etc/hostname
./etc/.pwd.lock
./etc/gtk-2.0/gdk-pixbuf.loaders
./etc/ld.so.conf
./etc/timezone
./etc/group-
./etc/adjtime
./etc/passwd
./etc/passwd-
./etc/ld.so.cache
./etc/osso-application-installer/certified.list
./etc/profile
./var/run/utmp
./var/cache/apt/archives/lock
./usr/var/cache/fontconfig/33a4131ab2947bcca2a0105cf2372d2e-mipsel.cache-2
./usr/var/cache/fontconfig/3830d5c3ddfd5cd38a049b759396e72e-mipsel.cache-2
./usr/share/doc/README
./usr/share/man/README
./usr/share/info/README
./usr/share/mime/XMLnamespaces
./usr/share/mime/text/plain.xml
./usr/share/mime/text/rdf.xml
./usr/share/mime/text/x-vcard.xml
./usr/share/mime/text/css.xml
./usr/share/mime/text/note.xml
./usr/share/mime/text/x-dtd.xml
./usr/share/mime/text/richtext.xml
./usr/share/mime/text/sgml.xml
./usr/share/mime/text/html.xml
./usr/share/mime/audio/x-real.xml
./usr/share/mime/audio/mpeg.xml
./usr/share/mime/audio/x-m4a.xml
./usr/share/mime/audio/x-pn-realaudio.xml
./usr/share/mime/audio/x-wav.xml
./usr/share/mime/audio/x-ms-wax.xml
./usr/share/mime/audio/x-ms-wma.xml
./usr/share/mime/audio/x-mp2.xml
./usr/share/mime/audio/x-mp3.xml
./usr/share/mime/audio/midi.xml
./usr/share/mime/audio/x-scpls.xml
./usr/share/mime/audio/x-amr.xml
./usr/share/mime/audio/x-pn-realaudio-plugin.xml
./usr/share/mime/audio/vnd.rn-realaudio.xml
./usr/share/mime/audio/x-mpegurl.xml
./usr/share/mime/globs
./usr/share/mime/image/x-xbitmap.xml
./usr/share/mime/image/gif.xml
./usr/share/mime/image/wbmp.xml
./usr/share/mime/image/x-ico.xml
./usr/share/mime/image/tiff.xml
./usr/share/mime/image/pjpeg.xml
./usr/share/mime/image/jpeg.xml
./usr/share/mime/image/svg+xml.xml
./usr/share/mime/image/png.xml
./usr/share/mime/image/x-xpixmap.xml
./usr/share/mime/video/x-real.xml
./usr/share/mime/video/3gpp.xml
./usr/share/mime/video/quicktime.xml
./usr/share/mime/video/x-ms-wmv.xml
./usr/share/mime/video/x-mp4.xml
./usr/share/mime/video/x-ms-wvx.xml
./usr/share/mime/video/x-avi.xml
./usr/share/mime/video/x-msvideo.xml
./usr/share/mime/categories
./usr/share/mime/application/x-ms-asx.xml
./usr/share/mime/application/vnd.ms-powerpoint.xml
./usr/share/mime/application/game.xml
./usr/share/mime/application/vnd.ms-word.xml
./usr/share/mime/application/vnd.ms-wpl.xml
./usr/share/mime/application/x-shockwave-flash.xml
./usr/share/mime/application/vnd.ms-excel.xml
./usr/share/mime/application/x-install-instructions.xml
./usr/share/mime/application/x-certman.xml
./usr/share/mime/application/ogg.xml
./usr/share/mime/application/news_reader.xml
./usr/share/mime/application/x-javascript.xml
./usr/share/mime/application/x-debian-package.xml
./usr/share/mime/application/pdf.xml
./usr/share/mime/application/x-deb.xml
./usr/share/icons/hicolor/icon-theme.cache
./usr/share/applications/mimeinfo.cache
./usr/share/applications/schemeinfo.cache
./usr/include/fakeroot/config.h
./usr/include/fakeroot/message.h
./home/user/.osso/keybindings.rc
./home/user/.osso/current-gtk-theme
./home/user/.osso/current-gtk-key-theme
./home/user/.suw_first_run
./home/user/first-boot-flag
./home/user/.osso_rss_feed_reader/cache/feeds/puhblxn
./home/user/.osso_rss_feed_reader/cache/feeds/rgxfucg
./home/user/.osso_rss_feed_reader/cache/feeds/stgtyat
./home/user/.osso_rss_feed_reader/cache/favicons/puhblxn.png
./home/user/.osso_rss_feed_reader/searchentries
./home/user/.osso_rss_feed_reader/feedlist.opml

For now I'm going to ignore all of those, except that I'll take that /etc/osso_software_version file and copy it onto my N800.

Obviously I don't recommend this partial install to _anyone_.. it's your own call alone. I'm trying to avoid having to reflash the image for now, so I installed only the kernel plus one or a few of the above files.