Upgrading to leopard has not done wonders for my Java development.
Here's a summary of my troubles:

- After upgrading, mysql didn't want to run. Found a solution for it
as some nice bloggers had similar trouble. Did not have to upgrade
mysql (well I cannot upgrade to latest version as there is no build
for it from mysql for Leopard).

- The upgrade made it so I had to reconfigure apache again with php5
and my setup for where I have my web stuff.

- Eclipse 3.3 started to bomb when using goto resource. Found that I
had to upgrade to 3.4 M3 (a port to 3.3 is probably in the works). In
3.4 code complete does not work. Installed Netbeans 6 beta 1 and it
works nicely (I miss a quick view of methods/variables for jump -
similar to eclipse meta-o - probably just newbie me that haven't found
it)

- GWT stopped working. This is fixed in a build with version 1.4.61
announced in a issue for GWT shell mode not working on leopard.

- phpeclipse isn't full compatible with eclipse 3.4 - ditto for
subclipse. It works though even some errors occure.

Besides that Leopard does look good, but I'd hold off installing it
until the projects get around announcing that they work fully on
Leopard.