A few people have written asking about and/or requesting Spring 3.0 compatibility.  There is at least one known issue, being that the <bt:jdbc-persister> tag generates errors during config parsing, there is a defect report that is tracking the issue.  However, <bt:xml-persister> and other config tags have been reported to work.  Spring 3.0 has not been extensively regression tested with beet, so this may not be the only issue you encounter.  However, it is the only issue reported so far.

"Official" 3.0 support will not be a feature of 1.4.0, however it will be the first priority for 1.4.1.  Fortunately, it sounds like it is possible to use beet with Spring 3.0, you will just need some workarounds.  The workaround for the <bt:jdbc-persister> bug is to not use the <bt:jdbc-persister> tag, but create an equivalent <bean> definition like so:

<bt:manager application="testTracking"
track-method-expression="execution(* com.mtgi.analytics.aop..*Tracked(..))"

<bean id="jdbcPersister" class="com.mtgi.analytics.JdbcBehaviorEventPersisterImpl">
    <property name="dataSource" ref="myDataSource"/>

That's more-or-less what the <bt:jdbc-persister> tag is really doing under the hood anyway.