Garbage collection took a big step forward with the advent of the Java language in the 90s. The Java community continues to push ahead on the garbage collection front today. The "Garbage-first" G1 garbage collector in Sun's Java HotSpot VM 14.0 is an example.
As described by Jeremy Manson, programmer, Google, the new collector splits the garbage heap into fixed-size regions, and tracks live data in those regions. How live the data is is key to decisions to be made on garbage collection. When garbage collection is required, the collector reaps from the regions with less live data first, writes Manson, hence the reference to "garbage first" in describing the new setup. For more read Garbage collector in latest Open JDK on his Java concurrency blog.
Downloading JDK 6 Update 16 is a step toward checking out this collector, still in beta as of this writing. You must have a copy of the Java Runtime Environment (JRE) as well. For more information check out Sun's Java HotSpot VM 14.0 information page. A preliminary version of the Garbage First (G1) garbage collector is included. This is an early access version on which Sun is seeking feedback.
Related garbage collection information
Garbage collector in latest Open JDK – Jeremy Manson blog
G1 presentation - JavaOne 2008
JDK6 SDK bundle release notes – Sun.com
Java HotSpot VM 14.0/G1 release notes – Sun.com