J2MEMap is a  Java application that displays scrollable, interactive Google maps on your mobile phone (Blackberries and other Java Phones.) In addition to displaying maps, it allows you to search for businesses by name and get driving directions. It supports both satellite and street map views. 

The program is responsive and does a good job of loading and caching
maps in the background as your scroll.  My GPRS connection isn’t fast enough to download as quickly as I can scroll, but on a faster
connection and with some UI refinements I could see using this a lot. 

Intriguingly, the author suggests that code might embedded as component in other apps. 

Warning: geek talk follows. (Normal people can feel free to stop reading at this point.) 

The ability to link from a page in one application to a page in another application is something that we take for granted in the web, but this ability does not extend to native applications. It’s difficult if not impossible to link from a web application to a native mobile application, or even link from one native application to a page inside another native application.

Interapplication linking is especially important and compelling for mobile devices, which lack support for multiple windows.

When I was at Microsoft working on the “Redshark” UI prototype, one of the ideas we explored was a uniform URL system that spanned resources in both web and native apps. 

This would make it very easy to create a web application that takes advantage of a component like J2MEMap to display interactive maps, for instance.  You could imagine adding a level of indirection so that the user could plug in their favorite map view application or web page.