Which network? I do not know yet, but I am sure that information will surface via the SEO forums when it does happen.
Matt Cutts, Google's head of search spam, announced this last night during his SMX session. He said that in the next week or two, Google will go after yet another link network. He also confirmed they did target a link network a week or so ago, but did not name which network was targeted exactly.
Like I said in the past, I am still surprised webmasters with long term goals for their web sites participate in these networks. Google has continuously gone after link networks in the past, even dating back as early or before 2006.
What can you do to prepare? Well, it is a catch 22. If you remove your link network links, your ranking will decline. If you keep them, Google may penalize the network and your site anyway. Long term - work on adding real links to your site and remove those network links.
Forum discussion at Google+.