At last, the new firmware has been made available for my Nokia 5800 XM. I've been stuck on V31 for what seems like ages, and didn't receive V40 at all.
It seems my product code (0575581) skipped V40 altogether, and went straight to V50. I'd checked availability before leaving home this morning, and got the usual result that V31 is all I could get. Lunchtime today, I check, still V31. Then at 2pm I check and bingo, there it is V50 at last.
Still, better late than never.
Nokia UK - Device Software Update – Can I update?