Is it not true that the majority of multiplatform PSN+XBLA new releases these days follow this pricing structure?
XBLA: 400 MSP (£3.40), PSN: £3.99
XBLA: 800 MSP (£6.80), PSN: £7.99
XBLA: 1200 MSP (£10:20), PSN: £11.99
...and do you not think MS will be tempted to bump the new release prices closer to or matching PSN prices when they start pricing stuff regionally?
I don't think it's as simple as that. This
comparison shows £7.99 games on PSN are either £6.80 or £10.20 on XBLA (800/1200 points). It's an old comparison and a very small sample but shows variation in who is cheaper.
Edit: I did a quick search on a couple of more recent games to see if that comparison still holds, and it appears that Dungeon Defenders is £7.99 on PSN but 1200 points (£10.20) on XBLA. Also, Joe Danger was released on PSN almost two years ago at £9.99, it's was finally released on XBLA last month for £10.20.