BIP 50: Proposed action items, including the hardfork, are completed.
BIP 60: BIP 37 was apparently not clear on whether the new "relay transactions" flag was mandatory or optional. BIP 60 sought to explicitly make it mandatory. In parallel, Jeff Garzik interpreted BIP 37's field as mandatory in https://github.com/bitcoin/bitcoin/issues/2534 and Pieter Wuille implemented the changes required for that (and BIP 60) in https://github.com/bitcoin/bitcoin/pull/2763 . Numerous forks of Bitcoin Core since then have also picked up this change.
BIP 64: The getutxo message was implemented for use between (pre-contentious hardforks) Bitcoin XT and Lighthouse. Both of these are unmaintained now, but this does not seem relevant.
BIP 66: Softfork accepted by a supermajority of miners.
BIP 73: Implemented by at least Bitcoin Core and BitPay.
This came up on the mailing list.
yyyy-mm-dd (ISO 8601) is the internationally accepted format for numeric
dates. This commit changes all BIPs to use that instead of dd-mm-yyyy.
It also updates BIP 0001 to prescribe the new format.