HP kicked those to the curb quite a long time ago.
Appears the last news for Cognos about Powerhouse on MPE was 2001.
In any case, the only stuff I can find even close to describing stuff:
[link|http://www.cognos.com/products/powerhouse/download.html|http://www.cognos.co...use/download.html]
A site which has quite a few links: [link|http://www.hp3000links.com/whatnew1.htm|http://www.hp3000links.com/whatnew1.htm]
Other than that, I can't find anything with teeth.