It is great to see them releasing data, but I'm surprised they went with something based on Socrata given there are other OSS products out there. I can't imagine how much they paid - I guess that won't be in the data catalog anywhere :(
Could you name some of the alternatives to Socrata, I really like what it does and its interface but would prefer something free.
There's http://ckan.org (disclaimer, I work with this) and http://dataverse.org if you're more academically minded. There are others, but hard to judge any claims of open-sourceness without access to source code.