Ooh, I hadn't even noticed that flac allowed for writing a padding block! With handy tags coming down the pipe, that will make flac REALLY nice for lossless encodings.
Just out of curiosity though: Wouldn't calculating the replay gain necessitate decoding the entire file? (That's still much less expensive than a full decode/encode cycle, I understand.)
At any rate, I'm sure that there's many of us who are patiently awaiting the next version of flac.

Thanks.
One thing I've noticed with my flac files though: When I run metaflac on any of them, I always get an "Error: short count reading metadata block data." The files test (and decode) fine though. This is running under Win XP on an AMD Duron.