I took a quick look at the TOC and didn't see a mention of web services. Much of my time over the last year has been spent creating web services or applications that consume web services. Most of the services I create use multiple databases. I've been using Spring for data access and creating my web services.
Will Grails make my life easier? Are there any compelling SOA related features of Grails?
Grails has RESTful web service support out of the box. There are also plugins available for some of the other web service libraries out there. As far as SOA I did run across this which seemed somewhat related.
As Gregg mentioned, there are plugins that add support for many popular web services frameworks, such as Axis2, XFire, CXF, and Spring WS. There are also plugins for Apache Camel, ActiveMQ and JMS(in general). And more are being added all the time. You can find more info on the Grails plugin portal: http://grails.org/plugin/home