Everybody loves the underdog -- until it comes out on top
This is probably the most obscure company on this list, but it's followed the typical trajectory outlined here, in its niche. Spring is an open source framework that was born as a reaction to the code bloat inherent to programming to Sun's official Java Enterprise Edition spec. Offering a core set of enterprise features that were enough for many developers, with none of the expense of writing reams of Java EE-required classes or buying an expensive Java EE-certified app server, Spring made for an appealing alternative to the mainstream.
But you know these things work: Spring became more ambitious, started offering its own app server. The company's founder, Rod Johnson, seemed determined not just to offer an alternative to Java EE, but to eclipse it. Some became convinced that writing code for the Spring Framework was becoming almost as onerous as Java EE code. And then the company was acquired by VMware, which quickly integrated it into its cloud computing ambitions, which involved deals with Salesforce.com and, yes, Google. Now Spring threatens to become a de facto standard of its own -- one controlled not by the open Java Community Process, but by a single company.