Do you feel vendor lock in as a real issue when developing a cloud application?

My company is developing a complex cloud application leveraging various features of AWS (EC2, BeanStalk, DynamoDB, SNS, S3 and some others).

Some of my colleagues are concerned about the vendor lock-in we're committing towards Amazon, but honestly I can't see how we could act differently nor why we should even consider a different solution, given how dominant AWS is in the cloud providers scenario. What do you think?