okay, yes I think it would be a useful feature - but perhaps I'm just using CSV export as a work around, what would be more useful to a wider audience I think is a option / widget that allows navigation of historical values in table form?
e.g. for an on off device or a scene controller (enumerated scenes) everything is currently presented as a line graph / bar chart and to see the history need to move the mouse back and forth to find historical data (the time that a pir detected motion etc) - not practical to look back to a previous week.
The MyNodes project has a dashboard widget type 'log' that shows a list of the time a message was received and the message value.
I appreciate that not all messages are kept (on off messages are but things like temperate are averaged out to minute, hourly, values etc)