It is polite to point out where in the article you found that figure. On page 6, the author states:
Sun�s JVM allowed the applet to allocate up to 60% of the physical memory, but not more. Software-injected anywhere-in-physical-memory faults: We were able to allocate N = 61,181 objects on a machine with 128 MB RAM. . .
Since the JVM by default has a default maximum heap size of 64Mb (java command documentation), the 60% figure is just about right. [ September 19, 2008: Message edited by: Joe Ess ]