Gruscheln is a German slang word derived from a shortening of the phrase grüssen und kuscheln, meaning 'to greet and cuddle (hug) someone'. Gruscheln is commonly used in both Germany and Austria, and has just recently entered into English internet slang.
The popular German social networking site StudiVZ uses Gruscheln in the same way that Facebook uses poke. (For those of you who don't Facebook, a 'poke' is just a way of saying 'hi!' without actually talking to the person; hit the poke button and it will send a small note saying "Tem42 poked you! Poke back?"). Internet geeks have a chronic belief that anything done in another language must be cool, and hence the newest bit of internet slang is being born.
Gruscheln and its mutant twin Gruschel (the imperative form) are still uncommon on English-speaking web sites. It is used by the uber-hip geeks to show off how worldly they are, but I predict that it is ripe for a crossover.