SP2 was the last fundamental change to XP's architecture (to the point that some programs that ran on SP1 *stopped working* with SP2). It added Data Execution Prevention and some other under the hood goodies. SP3 was basically a security update rollup with some essential hotfixes thrown in for good measure. Nothing major changed architecturally.
I just wish they would have released one final update rollup with all supported public updates to make it easier to get people up to a final patch level. Having to have 150+ post-SP3 patches makes things a bit cumbersome when fixing PC's for people that never upgraded.
When you go to hire a developer you're not just looking to hire someone who can code in the latest fad language/API/SDK. You need someone who knows software development like a captain knows his ship. I promise you that 20+ years of software development will be worth way more than the 22 year old kid who knows Ruby on Rails because he learned it while studying in college. That experienced developer can pick up whatever tool your company standardized on and yeah, it may be three months before he's all the way up to speed on it, but then the years of experience will begin to make themselves tellingly felt vs. a kid who happens to know the tool already.
Hiring for the tool is stupid. It would be like looking for a columnist who specifically has Microsoft Office 2013 experience and filtering all the applicants who only used Google Docs in their previous jobs. Either one of them can write copy.