I've just updated to a recent 1.4 snapshot and added in HABmin to the config without any real difficulties, so time to see if I can persist the temperature data and do a graph I think.
The rrd4j persistence service is set up to do just the right thing with temperature data by the looks of it.
To make the most of my very little machine (Raspberry Pi) I keep the config to a minimum, so here we go:
#add rrd4j persistence jar to the addons (org.openhab.persistence.rrd4j-1.4.0-SNAPSHOT.jar)
#rrd4j is already the default persistence service in the default config, so no changes needed there
#setup simple persistence config (configurations/persistence/rrd4j.persist) with 3 strategies for every minute, hourly and daily. and added temp sensor item to log every minute
#openhab.log shows sensor value being saved every minute and habmin shows the item in the persistence list, so will leave for a while to capture some data