It looks like lag.net is down, so the sbt install script cannot grab any of the required sources. Perhaps they should be moved to a different mirror and the install script should be changed?
Looks as though lag.net hosted projects have been moved to the twitter maven repo (http://maven.twttr.com). This is updated in StandardProject, but only as of 0.7.11. I'm sure they'll update that soon as they have in some of their other projects.
In the short term, you should be able to just add the above repo to your project config.
i think this is fixed now on trunk. if you update, can it find all the deps now?
[info] == update ==
[info] downloading http://maven.twttr.com/com/twitter/results/1.0/results-1.0.jar ...
[info] [SUCCESSFUL ] com.twitter#results;1.0!results.jar (335ms)