Penton Media, one of those troubled B2B media companies, is seeing more upheaval: John French, the CEO, is resigning. He will continue to stay on Penton’s board and will work with Wasserstein and MidOcean, the two joint PE owners of the company, on new media opportunities. Wasserstein & Co. purchased Prism Business Media from Primedia (NYSE: PRM) in August 2005 for $385 million…it was then merged with Penton Media in November 2006 and the combined entity took on the Penton name. Folio: French’s exit comes a month after Penton laid off 42 employees, and instituted a hiring freeze. The internal memo on his resig is also there.