I believe Franks enquiry was about realtime (ajax) pages rather than trends ?
The arrow indicates the direction of the last change so is more dynamic in terms of trend updates (note: arrows only appear on first change - I may implement a steady arrow to start with but haven't got around to doing that yet).
The beteljuice (and others) have experimented with this. Be careful how you present it !
A change is NOT a trend.
You appear to highlight 'new' until next check (or perhaps you have a long 'flash' rate ?) This may be confusing to the viewer.
When used the beteljuice had a 'flash timed' arrow for change next to the value, and steady arrow for trend.
As you will have discovered, an intitial change condition is impossible with js becuse it has nothing to compare it with, so don't 'lie' with putting an initial 'steady' condition, just creates more confusion.
BTW - I'm getting incredibly long download times with your site, problems ?
Also try to upload your cam pic to a smaller size (native 640 x 480) or use php to resize and reduce your bandwidth.