Read through to understand, and tested building and testing with hadoop23 and hadoop20, I checked the 624-2 patch against branch 0.5. I've not looked at your trunk patch yet, but I expect it to be okay, will do a quick verify before I +1.
Basically, looks good, and tests succeed. A couple of comments:
a) After I got into testing, I didn't read the jira comments till after I'd run them all and had the hbase tests fail. This is entirely my fault for not reading your instructions, but something I think people will hit when they download hcat and try running tests. Do you know if mvn artifacts for hadoop2 going to be published by hbase?
b) I see you changed some of the tests with pig schemas with parenthesis to not have the parenthesis any more, along with changing the pig dependency version. Should that be a separate patch by itself? I think it might make sense to separate 23-migration bugs with pig-upgrade and schema change bugs. Thoughts?