Just curious. Not that I would do that, but...

Doubt it.

no you cant

Nope. Only the BB OS will work on a BB.

nope, nope.com!

First, you would need a BlackBerry that accepted an alternate OS, and RIM is not about to do that.

Second, you'd need a version of Android written specifically for the BlackBerry device. Who is going to write that when A- you can't even use it, and B- only about 5 or 6 people would want it? You'd give up all the apps that make a BlackBerry a BlackBerry. Folks who bought BlackBerrys did so because they wanted the BlackBerry OS. There's always a few people who would do it "because they can", but only a handful.

Android has been a lot slower rolling out than I expected. I wonder if it's a little too open for cell service provider's tastes?

Android with a BB keyboard plus a touchscreen would be a nice combo.

go get a HTC dream/G1 then

It will have taken the hardware makers time to get used to android, if you look at htc now they have dealt with early issues they are bringing out a lot more models and other companies who weren't as eager are starting to bring out their first models now the early issues have been dealt with by them.