Stuck on finishing import (from external hard drive to computer hard drive)
If you are not sure if the process is actually doing something or just stuck, you can get an idea from the following

Activity Monitor
/Applications/Utilities/Activity Monitor.app   


See if the process is frozen. In that case activity monitor should
show the process/App (iPhoto in your case) in red color. If it is
red, there is a high probability that the app is "hung".  
See if the process is actually doing something on the CPU or Hard Drive.


If you see something going on there, it is highly possible that it is still doing something. 

If you don't see anything, you may want to check Console:  

Console.app
/Applications/Utilities/Console.app
Console shows error messages that the app may have generated to give some idea on what is happening.

Note that both these are indicative and may not be 100% accurate. In the worst case you may have to import again (I would search Google for any issues with importing large iPhoto libraries before trying again)

This is a snapshot of my activity monitor, I have selected QuickSilver and it shows 59.0 MB Bytes Read and 27.6 MB under Bytes Written. This data is dynamically refreshed so you can get a fair idea of the disk usage of an app. The same for CPU. Memory may not be a very good indicator though, even if an app has frozen it may still use memory.