Sony, is offering Home for free in order to make up for the horrid On-line support the PS2. Which wasn't Sony fault, they really over estimated the penetration of Broad Band internet.
The other reason, is that they are trying to undercut Xbox Live service in price. Although I am highly doubtful that Home will have the advantage that Xbox Live has, since MS has been do the whole Online thing for years.
I also think that Sony, is trying to offering to much at once, Home MMO feel will feel like its been duct taped.
But yea... Free Multiplayer that goes back a long time. Blizzard started it with Battle.net and at a similar time Bungie, though not to the extent of Blizzard, had a matching service as well.
Xbox charging is really a money thing. Which will probably works only here in the US. US likes to play together, but in their own homes.
In Japan, its not uncommon, hell its common as dirt for people to go to a home to play a multiplayer game.
And there Europe, but I don't know. It seems to be the empty lot of gaming markets. Everyone knows it there, but no one what to do with it. I have no idea what there multiplayer style is.