this. It explains the process of getting a new package added to the repositories.
The first thing I would suggest you do is search Launchpad to see if there are any needs-packaging bug reports for that package. If there aren't, please file one. An example needs-packaging request can be seen here.
If you are interested in packaging the application yourself, please set the needs-packaging bug to 'In Progress', and assign yourself to it. The Complete Packaging Guide will help teach you what you need to know to package the application. Once you have a working source package, you can upload it to REVU. Once it is up on REVU, you need to wait for 2 MOTUs to advocate the upload. If the package has some mistakes in it, the MOTUs will add a comment explaining what is wrong and how to fix it. Once you get 2 advocations, the package can be uploaded to the New queue. There, it needs to be approved by an Archive Admin. Once an Archive Admin approves it, it can enter the repositories.
One thing to keep in mind is that we are currently in Feature Freeze. This means that most MOTUs will be focusing on making Ubuntu more stable instead of reviewing packages on REVU. It also means that you will need a Freeze Exception in order for your package to be uploaded. If it is not urgent that your package be in Jaunty, I would suggest waiting until the Karmic repositories open up before trying to get the application uploaded to the repositories.