Luckily for those who don't like WikiLeaks or any other source of unsanctioned data, it looks as if Assange has finally pissed off enough people that he and it can't possibly survive much longer.
Unluckily for those hoping never to see their own companies embarrassed, others will pop up in his place to distribute embarrassing information on their company and others.
Remember F***edCompany.com, the site that invented the dot-com dead pool to give bitter techies and Webslaves a place to bitch about their companies and make anonymous accusations about management? It was eventually acquired and mostly disappeared. It had a huge impact while it was around, though, and set the tone for a lot of other snarky Web-company news sites.
There will be a lot of those cropping up after WikiLeaks is eventually crushed.
The only way to keep your company from being featured is to make sure you know what information is actually circulating through your company and use data loss protection or other security mechanisms to make sure you know where it's going and with whom.
The technology is a little challenging; it's hard to characterize and control unstructured data without making it impossible for users to share what they need to share. The politics is harder.
You'll never get beyond both at once, and you'll never plug every hole. If anyone could, WikiLeaks and Cablegate wouldn't exist. You can reduce the risk by a lot, though.