Was multi-sig implemented after Bitcoin/Bitcoin-qt 0.7.2? If yes, can confirmed transactions spent from or received at multi-sig addresses be validated by Bitcoin/Bitcoin-qt 0.7.2?
P2SH (commonly known as multisig) was implemented in 2012, before 0.7.2. P2SH transactions can be validated by earlier versions.
Do u mean blocks having P2SH transactions can be validated by first Satoshi client, i.e. bitcoin-0.1.0?