For most systems that I administrate, I keep a logfile 
which also includes when, which package was installed, removed 
or what ever. It would be a very cool feature for smart to provide 
such a logfile or hooks for it, as people would like to do this differently. 
Some might prefer a database, others a textfile that would need pre- or 
appending. 
 
For me this feature almost is a requirement for a package manager 
and we realised it with an apt shell wrapper that fires up an editor 
on the system logfile before the changes.