Manuel,
Sorry for the late answer - I think you may have found your way around the project.
Using Eclipse or JBDS should be fine.
The info regarding Snowdrop is at http://jboss.org/snowdrop, and the git repo is at http://github.com/snowdrop. You may have found this information already.
To wit, Spring provides an annotation scanner which can be pretty expensive for large deployments. The idea is that JBoss AS7 has the ability of indexing deployments for specific annotations, so my idea is to expand annotation indexing in JBoss to include Spring annotations, and then work around functionality such as org.springframework.context.annotation.ClassPathScanningCandidateComponentProvider.findCandidateComponents(String). There may be better extension points though to use that information. This could also require another MetadataReader implementation.
Some information about Jandex (JBoss' annotation scanner) can be found here: http://github.com/jbossas/jandex. I'll try to look for a better documentation on how this is currently used in JBoss AS7.
Cheers,
Marius