No, x10VPS is not free. The minimum-cost plan is currently $US 8.95/mo ($US 6.70/mo if you pay annually); you can see the plans here. The VPS servers are unmanaged, which means that you are responsible for everything (although you can get a turn-key initial "solution" including the operating system installation and a control panel). You need to be able to administer a Linux server to get anything useful done, and you need o be able to manage your own server's security. XMPP is possible, but you're going to need to have some high-priced bandwidth capacity if you want more than occasional text chat between a small handful of users.
Judging by what you've posted elsewhere, @Bobo, you've got million-dollar plans and a two-dollar budget (or less). Chat, especially if you envision going to voice or video, is extremely bandwidth-intensive. Social requires a lot of database storage and queries. Even a highly-trafficked forum can get to be pretty "expensive" in server terms. You'll need at least a VPS to get started, and you'll need to be prepared to spend some serious money if the thing takes off. The moment you can't handle the traffic, you'll stop getting any traffic, and "handling the traffic" can easily hit hundreds or thousands of dollars per month. Do you plans include ways to pay for it?