In the ever-raging PHP versus Java debate, there's no shortage of opinions to go around. Included in these thoughts is a new post from Julian with one of the more rational comparisons I've seen in a while.
In summary: a killer app in PHP will always sway me. But my recent hands-on experience with test-driven development has really underscored how essential it is to have good Agile development tool support.
He starts with PHP5, listing out the pros (performance, large community) and the cons (easy to write bad code, huge number of frameworks). Next up is Java - giving it the same treatment - the pros (rigorous typing, leads 'enterprise' tools) and the cons (behind the curve on tests, develpment timeframe slower).
There are several other he lists for each of of pros/cons mentioned above, so check out the full list in his post.