tell application "iTunes" playpause end tellAnd store it in your Scripts folder. I've saved it as itunesplaypause.scpt, and I've gotten LaunchBar to recognize it by typing ITP (type this, then scroll until you find the script, and press Return). Now, by typing ITP and pressing Return, I can play or pause iTunes.
You can make lots more scripts like this to extend your iTunes controls via LaunchBar. Open ScriptEditor and look at the iTunes dictionary.
[robg adds: There seems to be quite a fight brewing in the "launcher/do-it-all" utility category, with stalwart DragThing nearing a 5.1 release, a new LaunchBar, Butler (previously AnotherLauncher), and newcomer QuickSilver all going more or less head to head. Everyone seems to have their favorites, and it's sort of like arguing religion or politics when trying to sell someone on your launcher's benefits versus theirs! Personally, I use a combination of DragThing and Butler as my current fave team.]

