DROP INDEX performance/locking

We're taking some politically expensive downtime to drop an index
on a very large, heavily used table because to do it while live
blocks too many users for too long, requiring tens of seconds or
more on a system doing 200 transactions/second. That's due to
the fact that nearly every user interaction touches this
particular table.

It seems like one ought to be able to drop an index in a much
shorter amount of time and/or not block queries while it's
dropped. But I don't know the code well enough to say how hard
this would be.

Would a faster drop or non-blocking drop be worthy of a todo
item?

Ed