Contrary to what other commenters believe, this is the way that all PPC systems work - search for "Uber" on Google, Bing, etc and you're guaranteed to see a Lyft ad.
The Uber result for me also gives me 5 internal links to uber.com and a "more results from uber.com" link. Also in the sidebar I get a link to Uber's wikipedia page, as well as various information about the company, and links to competitors such as Lyft and Sidecar.
No it is not something Google allows. But for big brands they manually disallow paid results (see "Nike"). I don't see any ads on the uber results page.
Top result: ad - www.uber.com
Second result: ad - www.lyft.com/Uber_Drivers/Join_Lyft
Third result: organic - www.uber.com
There should be more results, but they aren't visible without scrolling down. Frankly, I find that more disturbing than anything else about this.