Ubuntu has a certified hardware list , which means that if you have (for example) an HP tc4400 , and this laptop is on the Ubuntu certified hardware list, then this laptop and all its components will work without problems.
For more details on what this "Certified Hardware" is, here's a link that explains it quite well: http://kernelpanic-colombia.blogspot.com/2010/09/certificacion-hardware-ubuntu.html
The thing is, they're hiring engineers to work in their lab in Lexington, Massachusetts . Basically, it involves testing hardware configurations, a lot of testing, and of course… working a lot with bugs and reports 
And well, that's all for now, here's the link to Canonical's website.
Greetings 
News source: AraPulido.