The spring framework is at version 3.0.5 for the general availability releases. There are many bugfixes and improvements in the newer versions, changelog here: http://static.springsource.org/spring/docs/3.0.x/changelog.txt
The main requirement for upgrading to atleast 3.0.3 is that Spring ETag filter for supporting out of the box Shallow ETags was fixed in 3.0.3 release. Etags can be used to saving bandwidth: http://www.infoq.com/articles/etags . Also,
RESTWS-6 may depend on this issue, if we want to use Spring shallow Etags in atleast REST calls.
If we have not many any custom changes to Spring libraries, it should be fairly simple to upgrade to the latest GA release.