on beta testing
Quick! What's the second word in "beta testing." If you said "testing", you're right. That's why beta testing should be run by the testing people in QA. However, as Paul Young writes,
If you run Product Management, especially in a smaller company, you may find yourself running the beta program. This is a tactical activity, and you will be knee deep in beta user qualification, feedback, administration, possibly even support, but you can take positives from a good beta.
Product managers are often involved with beta testing because product managers want to validate the usability of the product (hint: do it much sooner), they want to show the product to some key customers, or maybe they just know more customers than the QA people. Read Paul's description of 5 types of beta. Great stuff. Are there more?
Double, triple, etc leadership
Team in a wide definition of the term "team" needs both tactical/operative and strategic leadership. It can be better to have several peoples for several roles. But if your company is small or you managed to get an extremely widely skilled individual, he can be both a tactical and strategic leader - http://agilesoftwaredevelopment.com/blog/artem/product-manager-and-scrum-product-owner
In most of cases, though, I would recommend remembering what you want to be your main focus.



SaaS beta
The SaaS model is great in many ways, but the traditional concept of beta changes dramatically. The cycles are so tight they do not allow for conventional betas. I'm still working on/looking for a good answer to get valuable customer feedback from a product 'beta' when the product releases every month.
BTW, I agree that betas should be run by testing, but in my experience, the testing team is seldom willing to get that close to customers. <a href="http://leadonpurpose.wordpress.com">-Michael</a>