I have no experience developing applications for mobile devices, and I would like to know what criteria about an application or its target audience favor development as a web-based application in a mobile browser, vs. development as a native app or vice versa?
The things I did not know at first I learned by doing twice. -Billy Joel
Honestly it depends a lot on what you want to accomplish and how you plan on handling it. As Eric mentioned performance matters, a lot. If you application is 3D intensive you will probably want to stick with native development and include support for OpenGL or frameworks like Unity.
If you have a fairly simple web application that is mostly passing data back and forth (news aggregation, database management, etc.) then using a framework such as jQuery Mobile, Sencha, or even some cross-over frameworks such as PhoneGap/Cordoba or Titanium Accelerator may be what you are looking for. LinkedIn prides itself on it's web-based application.