This may be a feature, but as it differs from the behaviour in ADOM I thought I'd post it. (Or maybe it is simply a change that is yet to be implemented)...

The 'w'alk command is usable when in the presence of hostile monsters. I 'w'alked in the direction of an adjacent monster, and expected to get a message saying something like "Not while hostile monsters are present", but instead it worked! My character attacked the monster, killing it it one hit, and then proceeded to walk in that direction automatically.