I'm seeking recommendations for a CMS for a new community/ social networking website.

The following technical criteria are desirable:

• Open source (for customization and low cost).
• Linux-Apache-PHP-MySQL based (technologies I already know).
• Job board module, i.e. employers can advertise jobs and members can manage resumes and apply online.
• Forums.
• E-commerce module (see below.)

Initially the site will have two revenue streams: Google AdSense and sales of job ads to employers. Eventually (once the membership has grown) I would like to sell banner ads.

Now the kicker: I want to sell employment ads using credit cards. And most importantly, it needs to be Payment Card Industry (PCI) compliant. So I'll need an e-commerce module as well. I'd like something robust that can simply handle things like discount promo codes and purchase order payment for preapproved customers.

In general I've heard good things about Drupal. Their ecommerce module recently fixed a PCI-compliance bug (something about writing customer info to a log file), so it seems that they're focused on this issue. But I've been unable find some definitive statement about PCI compliance.

Any and all suggestions are greatly appreciated...

or you could try joomla, which has a larger community support base as compared to drupal.

I'd second that suggestion to try Joomla.