lock - yes
logged off - install HFS as service (search the forums)
standby:
S0 on - fully operational
S1 standby - I think it can still work if your NIC is operational in this mode
S2 suspend - if your NIC is operational and can wake up the system it's possible with a small delay
S3 suspend to RAM - you'd have to wake up your system with a magic packet (Wake-on-LAN), delay before it's operational
S4 hibernation - same as S3, there would be an even longer delay
S5 soft-off - same as S3+S4, but additionally you'd have to wait for the system to boot and start HFS