The only other major mainstream products that start with Play that we know of are Playboy and Playmobil (and plug and play), hardly business oriented products; we're therefore puzzled as to why RIM chose to name its Blackberry tablet as the Playbook.
In the US, a playbook is a notebook containing descriptions and diagrams of the plays that a team has practiced and sounds a lot like Facebook.
However, RIM doesn't even own the domain name Playbook.com - it's owned by an individual and points to a website dedicated to Major League Baseball - nor does it related to anything in the current Blackberry portfolio.
For example, Apple's obsession with whatever starts with the letter "i" (iPod, iPhone, iPad, iTunes) is legendary and follows a well defined trend. Ironically, Blackberry had already purchased the domain name Blackpad.com but as it stands, it doesn't redirect to anything at the time of writing.
Instead, someone at RIM chose a playful name to describe a professional grade device that's supposed to be RIM's answer to the Apple iPad. However, a name carries so much weight that it is supremely important to get it right in the first place.
Toshiba went for something elegant like the Folio, Avaya introduced the enlightened Flare tablet while Cisco went ahead with the neutral-sounding Cius. That said, the Playbook is not a bad product - don't get us wrong - it has some very real potential.