Hi there
I've also come across that certification. As for now, I haven't really found any 'official' preparation material.. There is one page I found with an unofficial (apparently) software to prepare for the certification:
http://www.epractizelabs.com/certification/sun/oce-jpa-exam-6.html I actually read about it on this board.. So does anybody have experience with that software? Has anybody in this world ever taken that exam at all? ;-)
As for books, this one doesn't look too bad:
http://www.amazon.com/gp/product/1430219564?tag=jranch-20