The ~/.thumbnails directory grows without any size limit at all, and is never cleaned.
This isn't really a nautilus bug per-se, since many apps write thumbnails here. What we need is an app that can be run at various times (such as login) to remove old thumbnails based on some per-user settings (max atime age, max total thumbnail dir size, etc).
Assigning to desktop lead. :)
Alex I'd say be sure there's a gnome.org bug for this and UPSTREAM it.
Well. Its not really a gnome.org only bug either, since the thumbnail spec is a freedesktop standard. But yeah, there should be an app to limit this in gnome. Upstream bug: http://bugzilla.gnome.org/show_bug.cgi?id=151216