Doesn't Quicksilver already offer this same functionality? I'm also unsure if I would use this app.
ctrl+space
"Mail"
cmd+n
"person@example.com"
tab(x3)
"Subject"
tab(x5)
"Message Body"
shift+cmd+d
Tabs may vary.I would have no use for the original app in the link, I mean how hard is it to just do cmd+tab and cmd+n in Mail ?