I'm having this same problem. I've upgraded from 7274 to 7312 (on ubuntu) and I lost the ability to import maven projects with multiple modules.
Here is my parent pom.xml:
http://svn.codehaus.org/trails/trunk/trails/pom.xml
You can download the whole project from there.
status update:
I'm using release 7.0.1 (build 7634).
If I replace references to ${*.version} with version numbers, I does import OK
The "soft links" workaround also works, but then I have to create files like:
~/.m2/repository/hsqldb/hsqldb/${hsqldb.version}/hsqldb-${hsqldb.version}.pom
~/.m2/repository/hsqldb/hsqldb/${hsqldb.version}/hsqldb-${hsqldb.version}.jar
Which is not only painful to do, it also doesn't let me use more than 1 different version for the same library.
I still think that Idea should be able to import projects that are using "<properties>" to define libraries version numbers.
Maven 2.0.7 does validate the project.
see http://www.jetbrains.net/jira/browse/IDEADEV-22126
In build 7364 I have replaced maven and maven-web plugins, with the versions from build 7274, and it looks like everything is working now.