Android signing signs..

I hope this is how signing will be done even in Android devices:

There are no requirements on the key used to sign .apk files; locally-generated and self-signed keys are allowed. There is no PKI, and developers will not be required to purchase certificates, or similar. For developers who use the Eclipse/ADT plugin, application signing will be largely automatic. Developers who do not use Eclipse/ADT can use the standard Java jarsigner tool to sign .apk files.

Taken from http://code.google.com/android/RELEASENOTES.html. This is the major problem with J2ME in my opinion: no way for developers to self-sign stuff.