Yeah that's a bit nuts. So i can give a fullscreen presentation via HDMI. Powerpoint for example or a Video file and have my cheat-notes / script on the tablet.
Of course a laptop can do this, but perhaps not so seemlessly. And you'll need a heavy duty laptop to play 1080p video via HDMI and a 3D game simultaneously.
On another note:
MLB (NBA, NHL, soccer, etc.) need to make apps for the Playbook. Currently these are some of the biggest selling apps for iPad in terms of gross profit. (each app sells for around $15). Currently in the U.S. to order the MLB channels in HD is around $70/month, with the app it's only $15 to watch the favorite sports teams in HD. As a side note, MLB has stated that they sell approx 4x more iPad MLB apps than on Android.
On the iPad forums a lot of people are currently buying iPad2's and MLB to output the game on their TV via HDMI. A lot of frustration though because the MLB app currently can't output full screen via HDMI, I suspect a fix for this will come eventually though.
On the playbook it would allow fans to stream their fave sports game + output via HDMI, and multitask / display sports stats on the tablet itself, or the app could put realtime stats of the current player & bat, hockey player data, etc... on the tablet screen... or possibly even record part of the game like a PVR. Maybe allow some of those sports folks to watch the game and multitask via a website to a chatroom to discuss the game in real-time with other like-minded fans.
A lot of possibilities here for a huge market that's willing to pay money.