I used Surf for a while to write some Alfresco Share extensions and I really like its ease of use when writing REST applications.
However, I haven't seen much activity on the project lately. The JIRA's roadmap has a 1.0.0 final release planned for November 2010 from which only 3 of 21 issues have been finished. Recent activity was all related to bugs.
This makes me wonder what the plans are regarding Spring Surf. Is the project still active?