Got a blast from the past today, a colleague forwarded an old email I wrote on 6 June 2006 at 1:28 pm! Wow. I said …
…pointed out recently we’ve been being naughty using KB for kilobytes, when it should be kB. k for kilo is the standard (it’s still M for mega, G for giga) and although bits/bytes aren’t standardised b (bit) and B (byte) are in common use and thus recommended.
It came up as the team there were debating whether to use KB or kB (not KiB? nobody loves kibibytes it seems). I guess it doesn’t really matter, people tend to understand in either case, and I reckon file sizes should probably be rounded up anyway, so long as they give an approximate guide to downloading. But I can’t help thinking — everytime I see “32 KB” — my, that’s a cold, cold file! (K is for Kelvin in SI units). KB is also my sister’s initials. But I don’t think she’ll mind too much if you use it on your websites!
Ben Boyle lives here! 
If it's any consolation, the JEDEC standard (all be it for solid state memory) defines KB = kilobyte = 1024 bytes. KB = kilobyte also seems to be accepted in common use due to it's use within certain Operating Systems 🙂