I'll be very interested to find out what role Guido will take up at dropbox. When someone like Matz/ Guido/ etc gets hired, what do their job responsibilities, for the community include exactly? Are language writer hires such as this purely symbolic?
Having worked with Guido on App Engine, I believe I can answer this. Just because someone wrote a language doesn't mean they have no other talents as engineers. I will say that apart from being a good language writer, he is also a good Engineer. For us having so much invested in Python, Guido has been an important part of App Engine. But even if that wasn't true (as it may be for Dropbox), having well-known programme…
He also did Mondrian, which kicked off the trend toward web-based code-review and was a huge step forward from just critiquing patches over e-mail.
Usually famous programmers get famous because they've done a lot of programming; that experience translates into some pretty cool programming chops.