I recently found out I could use qlop -gH package or qlop -tH package to get merge time:

http://farm2.static.flickr.com/1010/5190755414_3fef86bebf.jpg

But it doesnt have an option to list packages merged in a session. So I wrote one to parse /var/log/emerge.log on its own, last-merge-time.sh:

http://farm2.static.flickr.com/1039/5190755456_e4530fd6a5.jpg

I tried to mimic the result format.

The merge time calculation is different than qlop, you might see difference in a few seconds. The script uses sed to filter unwanted merge log and keeps the last merge, then uses awk to format the output. You probably noticed that interrupted in the screenshot1 above, its a result of user interruption (pressing Ctrl+C) while merging. The timestamp is the start time, not the end time of merging as shown by qlop, I am just too lazy to change my code.

Of course, there is also the last sync time.

[1]The screenshot shows the result by feeding the script with hand-modified raw log.