Comment 2 for bug 220181

You can use gDevilsspie/Devilspie to partly fix it, creating a rule for your Screenlet like this:

( if
( begin
( contains ( application_name ) "Screenlet.py" )
)
( begin
( set_viewport 3 )
( println "match" )
)
)

However, it does not work when Screenlets are cloned from a service, if I unerstand it correctly. And you can always make a Screenlet "Sticky" in order to make it appear on all workspaces.