I'm not sure how often this page is updated yet. PS3 data looks incorrect, so hopefully a patch can fix this soon. (Unless only three people have really finished the game on PS3, vs 1700 on 360). Actually the data looks completely broken right now as it is reporting 48 billion lost souls on PS3, but only 12 billion on 360. The site also features a network status widget for both platforms with placeholders for the PC version, which does seem to be current as it is reporting tonight's upcoming PS3 server maintenance.
Data tracked includes worldwide deaths, how those deaths occurred, souls lost, percentage of players that are human vs hollow, and more. The images also change quite often, but what the detail in the images represents is unknown. See below for comparison of one section.
edit: Looks like most of the data is inaccurate. 360 total deaths show nearly 3 million, but the breakdown only adds up to around 10% of that figure. I'll check back with it periodically to see if and when it gets updated.
Also, check out the differences in detail. The number of candles on the left hand side of the image also varies drastically between versions, with the PS3 presently having far more.