No. It is a deprecated, non-standard value; you should now use CSS to get the same effect. There are plenty of code examples using the "vertical-align" property out there, just search the Internet for answers on how to do this in a standards-compliant way.
Re: Image alignment - absmiddle
Documentation Manager, CKSource
See CKEditor 5 docs, CKEditor 4 docs, CKEditor 3 docs, CKFinder 3 docs, CKFinder 2 docs for help.
Visit the new CKEditor SDK for samples showcasing editor features to try out and download!