ever since Facebook blocked my account for a little less than a day people have been calling me with some real sob stories about how their accounts got turned off by Facebook and that they have no recourse.
What to do? Just don't join networks where the primary value is locked up inside them. If you don't control most of your content don't join (and if the value is locked up inside their system don't bother, or at least don't invest much time at all so little is lost in the event of a problem).
Hoping companies will care and be competent enough to manage what you invest in creating just doesn't seem like a worthwhile risk to take to me. They will have all sorts of issues to deal with and either out of plain bad management or because they decided it is easier and cheaper to destroy (deleting it, breaking support for code you relied on...) what you have created they are very likely to not value your investment. Most likely, only if their belief of what is in their interests happens to align with what is in your interests will you be in someone decent shape (even then you are susceptible to them managing poorly).
For social networks I can see they might add value by providing useful tools to improve connections (but if they can't figure out a way to be open and interact easily with mainly internet based content don't waste your time with their old proprietary thinking model). I just don't see much need to participate in an enterprise where I would have to invest my time and energy and content and hope that the company decides not to be evil for the rest of the time I want to deal with them.
Keep most of your content under your control. For example even if your content is in Blogger, the ability to backup (and move) your blogger blog essentially leaves the content in your control. Then if Google decides to be evil you just take you backup and post it elsewhere.