I did that - my IM client was on permanent 'away' status. I was tired of being 'green' and people would send multiple messages if I didn't respond instantly to their IMs.

Being permanently 'away' meant people could still contact me and I could respond when convenient without disrupting my work.

I very much subscribe to the convention that proximity should determine how much communication should interrupt what you are doing. Face to Face > Phone/video Call > IM > Email