Dropping unique constraint on PostgreSQL table taking 10+ hours
Step one - go into task manager, have a look and see if anything is actually happening. If you can't see a lot of cpu and/or disk bandwidth then it's not doing anything.

Step two - check what PostgreSQL says is happening. There are two system views useful here: pg_stat_activity and pg_locks. See what's in both. The database/relation numbers in pg_locks are internal OIDs - try SELECT OID,* FROM pg_class to see which tables/indexes are being locked.

My guess is that the system is idle and it's just waiting for an exclusive lock on the table in question and something else is blocking it. The two system views should show you what is happening though.