I have recently given a series of lectures on our taught MSc Communications Software course on "The Rebel Platforms", a term used by Richard Monson-Haefel, an analyst with the Burton Group, in that group's regular conference (c.f. the IT Conversations Podcast. In this he includes both LAMP and its derivatives, and alternatives to monolithic J2EE in Java such as structs, Spring and Hibernate. This he identifies at least 4 major platforms: Java/J2EE, .NET, Java/rebels, and LAMP/derivatives.
Interesting to see some active debate on what the impact of dynamic languages on the Java Virtual Machine (JVM) as a platform is ongoing LAMP and Java (ongoing, Tim Bray's blog)) that references Sun Analyst Conference: Good News/Bad News (tecosystems - Stephen O'Grady's blog). This includes those who use specific version of those dynamic languages that target the JVM: "Jython and JRuby and Caucho (as in, PHP on the JVM) and so on".
Tim argues:
So the first thing we have to do is to stop mixing up the Java Language and the Java Platform, and make it clear to the world that other languages - in particular dynamic languages - work fine on the platform, and that there's nothing wrong with using them. Then we have to do some engineering work to help this happen. The good news is, we're getting started on that; see Gilad Bracha's article and slides on the JVM-level progress. But that's way down in the engine room; I think we need to help out all the way up and down the stack; the profilers and debuggers and IDEs and, well everything. But still (call me a marketing droid if you want to) I think the message is the important thing: It's time to grow and share the Java platform; everybody wins.
The impact of JVM as a virtual machine for dynamic languages is balanced by the potential impact of an emerging new virtual machine designed for dynamic languages, Parrot, a spin-off of Perl 6 activity, that felt the next version of Perl needed its own VM, though the idea is now to optimise Parrot for dynamic languages in general.