Once I bought a domain with a poker room name on it. Asked for permission first, it was allowed. I was about to launch the site, contacted the company to get a bonus code, and they told me it was not permitted to use their name on the domain. I transfered the domain to them and got a bonus for the misunderstanding.
With Poker Stars, I almost bought a good domain with their name in, but talked to Carly before that, and they told me not to do it.
My point is: if you want to go that way, ask first, and be aware that they may change their mind at anytime, so I wouldn’t invest a lot of money in such domains.