BBC One is HD as well - it is just that the regional news in England isn't at the moment, and that means the HD version isn't 101 on Sky / Virgin / Freesat's EPG or 1 on Freeview. Switching for just the one programme appears to be an issue for at least a large number of viewers - which is why just having it on the iPlayer isn't really the objective of the exercise. It should also be said that the 6pm hour of national and regional news is relatively highly viewed (as it is on ITV).
ITV Region: ITV News London
BBC Region: BBC London News
I tried watching South Today on iPlayer and it's really hard to tell if it's a downscaled version because the PQ is shocking, despite it being 960x540. BBC London, Spotlight, Look East (West) and North West Tonight are clearly downscaled.
ITV Region: ITV News London
BBC Region: BBC London News
I've managed to watch South Today on Sky tonight and it does look downscaled from 1080i.
The last I had heard (before I left the organisation a few months ago) is that the opt-switching work had been completed in all regions to allow centralised opting, but with soft-opt abilities retained. This is part of the work required for BBC One HD English Regions.
Southampton is the first region to get its gallery/control room upgraded as part of a new roll out across England. It includes new infrastructure, automation and cameras. This is all HD but the installation may not be fully complete yet or they may still be testing. For example the South Today end board had a transition effect but the name captions still appeared to be from an old output. The reason for the new screens in the studio is that the previous back projectors were SD (and very old) and would look terrible on an HD output. Presumably a cost/flexibility decision has been to go for monitors rather than projectors. Or it may be a temporary solution. The plan is to roll out the new gallery infrastructure across all regions part from London, Salford & Plymouth as they already have HD infrastructure.
Excuse my pretty poor knowledge on how these things work, but are these HD region listings not more likely to be something to do with the iPlayer live streams? We know that they have a revamp ready to go which is pretty radically different (see the current beta) so it seems plausible that these listings could be linked to the expected launch date of this.
What do we currently see when we watch BBC1 live on iPlayer? Is it a HD feed (including when regional news is on)?