I created a web project with maven like this:
mvn archetype:create -DgroupId=com.mycompany.app -DartifactId=my-webapp -DarchetypeArtifactId=maven-archetype-web
Just install a development version of m2eclipse and your project will be used as a maven project, no need to do mvn eclipse:eclipse or anything like that. I use it and works.
http://m2eclipse.sonatype.org/