Here are the file sizes using the 1.4.2_03 Linux Javac tool with no debugging (size with full debugging info in brackets).
No optional packages - 340K (457K)
All packages - 626K (837K)
All packages bar test - 487K (657K)
Just out of curiosity, I've been trying out the 'pack200' util in java5 (beta2-b51) on various jar files and with xith3d I get these numbers:
Plain jar - 702,073 bytes
Packed jar - 393,776 bytes
Packed and gzipped - 175,495 bytes
which is almost exactly 4x compression
Not quite the '8 fold' compression they claim but still not to be sniffed at.