How do I open terminal or browser windows in the current workspace?
I've set up Alfred to open new Terminal and Safari windows in the current workspace by having it call an Apple Script. I'd expect that you could do the same in Quicksilver. These are the scripts I've used:

Safari:

tell application "Safari"
  make new document
  activate
end tell


Terminal:

tell application "Terminal"
    do script "uptime"  
    activate
end tell