I personally wouldnt mind having one, as i like to use a looper pedal and not having to change guitars would be awesome.
I had a mazeti one a while ago, it was a 7/5 string one with a floyd rose. It was massivly heavy, but awesome to play, and got a ton of looks from people as i was taking it to the music shop to sell.
Ive seen a few people make them from chopping up a squier strat and P bass and sticking them together.
With regards to makes, rickenbacker made one a few years ago, and shergold did one. Charvel and washburn have had a go at doing a few too, danelectro too, and even alembic.
Anyway, here are some pictures that ive collected of some awesome ones:
Shergold (they actually did a detachable one too)
Charvel
Home made strat-p
Washburn, i think
A ricky
Alembic
And a cool looking one
And heres a danelectro, hillel from chili peppers played one in the movie "thrashin"