Actually a good portion of BBCA is real HD. While the Brits are a bit behind us (for once) in HD content, things are gaining momentum as shows such as Doctor Who, Top Gear--most of BBCA's prime-time schedule is in true HD as they were produced so in the UK, but not necessarily aired in the UK domestically in Hi-Def. Unfortunately, BBCA still airs a lot of old standard def that looks it, but still improved from the SD BBCA Dish channel.
I'm unaware of any SD wide-screen programming on BBCA that has be "upconverted". I am aware of UK wide-screen programming still in Standard Def, but airing on BBCA HD. The effect is something like one would expect if it were "upconverted." It's just that almost any SD is going to look a lot better than it does on the standard def channel.