Hi Gary, this works for me. A problem with your build definition maybe?
tmp$ mkdir foo
tmp$ cd foo
foo$ sbt -sbt-create
Java HotSpot(TM) 64-Bit Server VM warning: ignoring option MaxPermSize=1024m; support was removed in 8.0
[info] Loading global plugins from /Users/rnorris/.sbt/0.13/plugins
[info] Updating {file:/Users/rnorris/.sbt/0.13/plugins/}global-plugins...
[info] Resolving org.fusesource.jansi#jansi;1.4 ...
[info] Done updating.
[info] Set current project to foo (in build file:/private/tmp/foo/)
> set libraryDependencies += "org.jsoup" % "jsoup" % "1.8.3"
[info] Defining *:libraryDependencies
[info] The new value will be used by *:allDependencies, *:dependencyPositions
[info] Reapplying settings...
[info] Set current project to foo (in build file:/private/tmp/foo/)
> console
[info] Updating {file:/private/tmp/foo/}foo...
[info] Resolving org.scala-lang#scalap;2.10.5 ...
[info] [SUCCESSFUL ] org.jsoup#jsoup;1.8.3!jsoup.jar (2332ms)
[info] Done updating.
[info] Starting scala interpreter...
[info]
Welcome to Scala version 2.10.5 (Java HotSpot(TM) 64-Bit Server VM, Java 1.8.0_65).
Type in expressions to have them evaluated.
Type :help for more information.
scala> import org.jsoup._
import org.jsoup._