listsinceblock always return zero transactions for recent blocks. This bug is critical for web services. Steps to reproduce:
$ bitcoind getblockhash 248190 00000000000000448f3785854bcda4434e9f115b53f0fa8d377ac7c09af47007
$ bitcoind getblock 00000000000000448f3785854bcda4434e9f115b53f0fa8d377ac7c09af47007 "hash" : "00000000000000448f3785854bcda4434e9f115b53f0fa8d377ac7c09af47007", "confirmations" : 1, "size" : 102397, "height" : 248190, "version" : 2, "merkleroot" : "73fbda07f60b92b6cbeb4908e8af7a2e871ad4fcb75c04937d330544dfcbaa1c", "tx" : [ "6dafe311456554cd2b381229b89e34abb00c1c909e078ee4186d360af1c15c30", "3323f4a46984591704550b752c14307b1285f3019b6627793e56373edf3c0ef8", .... at this point we are sure that there is a lot of transactions in since previous block (248189) $ bitcoind getblockhash 248189 000000000000004cbc5f56e8684700aae0a81de7ea501b8be8d0302a0d144168
$ bitcoind listsinceblock 000000000000004cbc5f56e8684700aae0a81de7ea501b8be8d0302a0d144168 { "transactions" : [ !! EMPTY LIST !! ], "lastblock" : "000000000000005b96750e89499168fb0ca8bd6d0efdc858a9e3340eea2614aa" }