St. Patrick's Day Cake?  

Chocolate stout cakes sounds pretty good. A friend at work made one for our St. Patty's day party and it was amazing. It was so moist, and not too sweet. It went perfetly with the Guinness ice cream he made too!
For your party might I suggest cupcakes? While maybe slighly more work, they keep better, and can be made and transported in disposable cupcake tins. They are also easier to eat...no need for plates and forks. If you parties are anything mine, there is always way too much food, and the cake often goes untouched....unless you need that all night sugar buzz for playing karaoke :-)
As for decorations, there is the traditional clovers, pot of gold, rainbow, lecrechaun thing. But maybe you could also encorporate some other things...the colors of the Irish flag, some snakes (Isn't it said St. patrick drove the snakes out of ireland?). If you are feeling really ambitious, maybe some kind of celtic knot design.

Have you aver seen the movie, Boondock Saints? There is a painting of the Irish flag on a wall in the background that is pretty awesome. It has some Irish saying on it that most of the Irish guys I know lover from them movie. If your friend is Irish, ask him about the painting. He'll tell you what it looks like and what it says. It will certainly be a non-traditional cake if you decorate it like the flag in the movie painting.

That does sound delicious. I am not sure, but I may have had something similar in the previous year, and I do remember liking it, it was blueberry. I like blueberry a lot more than cherry. And, I like pineapple too. I am not a big fan of fruity cakes, but this sounds like the one I had before.