As rumors grow that social network Facebook will introduce its own payment system, News Corp.-owned MySpace, still the leading social network, is teaming up with PayPal, eBay's online payments division. The partnership amounts to an experiment at this point, focusing on donations to political campaigns and nonprofits — not exactly a hotbed of MySpace activity. Wake us when you can buy concert tickets on MySpace. But the move does speak to the partners' fears that Facebook will introduce its own payment system. How to respond? Become frenemies, of course. MySpace instantly has a proven payment system without months or years of development, and PayPal gains access to MySpace's millions of users. Nothing builds partnerships faster than fear of the competition.