all recent lm_sensors versions are masked and only accessible via ACCEPT_KEYWORDS="~amd64". The 2.8.6 version however seems to install and works perfectly well on x86. Now that the 2.6 kernels are out, it would seem to make sense to at least include it for testing. alternatively, the more recent versions could be placed in a separate development-lm-sensors package similar to development-sources.
stable since 20 Jul 2004