What a jump, I'd be curious to hear first why anyone would prefer Intel above pretty much anything else, but also secondly how the actual experience difference between the two after working at both, must be a very strong contrast between them.

On her website it says she is working on GPU drivers there - I wouldn't be surprised if that's something she greatly enjoys and Intel gave her then opportunity to work on official, production shipping drivers instead of reverse engineered third party drivers.

If I were Intel, this sounds like a great person to give an R&D skunkworks dream job.

Potential lottery ticket win, they are available for consulting internally anywhere that can add value, and they're not working for anyone else.

I imagine there's also some challenging work that would be fun to dig into. Being the person who can clean up Intel's problems would be quite a reputation to have.

Maybe she was given a huge signing bonus to avoid her working on making X86 irrelevant? Combined with perhaps some interesting project to work on for real.

I'm sure most would stay at valve if they could. The just do so much contract work, and I'm sure a stable job at intel is better pay, benefits and stability.

Would it shock you to hear that many/most engineers don't pick an employer based on brand reputation?

usually a combination of money/benefits/locale is the answer to this question