Yes, I have seen versions numbers for platforms on CV's. I have them on my CV and I look for them in applicant CV's. I'm a Linux admin who manages two student interns (Jr. Admins). I do the screening of my interns as well as helping to screen full-time co-workers. When reading CV's, I give a higher weight to those with version numbers. I'm not too worried about minor numbers (i.e. RHEL5.4 vs. RHEL5). I'm not too worried about older versions. Version numbers act as a shibboleth to weed out the posers from those who have actually worked with a technology.
When interviewing a potential Linux admin, I always ask what version and flavour of Linux that they have experience with. If they can't give something credible, then I don't rate them as having that skill.