It is not limited to the Marketplace.
I didn't understand! Do you mean posts in Marketplace or including all the child boards? Bumps in the child boards happen to be deleted before.
-MZ
It is a marketplace rule, and will primarily apply to the marketplace threads, however there are reasons to bump threads throughout the entire forum and you can bump them as well. If you were to bump a thread in say bitcoin discussion more then once per 24 hours then it would likely be considered spam, although the definition of a bump in other parts of the forum (outside of marketplace sections/child boards) is going to be more literal.
For example if you have a marketplace thread and need to give some kind of update then you should edit one of your previous posts (most likely your OP), however if you have a thread in bitcoin discussion and there is some kind of update then it should be acceptable to post such update.