Can prepopulate be more dynamic

This is a good module no doubt. And it seems to be the only module out there that can actually solve the problem of prepopulating fields. I have gone through the documentation and all the examples provided are somewhat static to me. For instance, an example such as this;

http://www.example.com/node/add/blog?edit[title]=this is the title&edit[body_field][body]=body goes here

where the [title] value is just manually written will not solve real life problems. My question is can't the value of a variable be dynamically replaced? Something like getting the value from a dbobject and setting it in the url.

Another thing I find confusing about the prepopulate module is in terms of implementation. When implementing are you suppose to write a custom module in order to embed these variables in the url or one has to embed the variables manually as at when the url is requested (something like a trigger) or maybe variables can be embedded using the preprocess functions in a template.php file.

Please i need some clarity.

Thanks