system-level testing, what's a project manager to do? New project managers don't necessarily have all this knowledge, but if they manage the developers and testers in a project-based team, they will still need to learn so they can help each team member with career development opportunities.
I'm not a fan of certifications, so I don't advocate people being sent to certification courses to learn how to do a particular form of testing (or project management, for that matter). Instead, consider team-based learning. Select some books that explain peer review or testing of some sort, read them chapter-by-chapter one week at a time, and then discuss them in team meetings. Have each person try something from each chapter once a week. In the course of a year, you can get through three or four books, applying what the books suggest. Since you're learning as a team, you've helped everyone learn and apply something new-a form of career development. (The cost of all the books for everyone on your team is significantly less than the cost of a certification class.)
If you don't like the idea of team-based learning, consider reading the books yourself. It's harder and less likely you'll be able to get through everything in a year, but it might be worth a try.
An alternative to reading books is attending experiential workshops. If you have the money, bring in an expert to train your staff in some form of testing. The best way to do this is to have the expert train your staff and then, immediately after the workshop, help the team members apply their newly discovered knowledge to their products with the expert's help.
Another option is to consider sending your entire team to a conference. At a conference, you'll each have a chance to try different tutorials and attend different talks. If you meet as a team in the evenings to debrief, you can select the tutorials and experts you like best.
Whatever you choose to do, make sure you don't try to learn everything yourself and then "teach" it to your team. As the project manager, you will run out of time and then you'll be ignoring everyone's need for learning and career development.
Project-based teams can help the organization develop and finish great products faster than matrixed or functional teams. But they place an extra burden on the project manager not just to manage the project, but also to manage her learning curve. Consider what you and the team members need to know, and consider leading the team in learning and applying that learning to your project. Everyone's career will soar.