Security vulnerabilities in mobile sites

Seems a lot of high profile web services are starting to deliver mobile contents these days. This is great and I really believe in more people will use the web on their mobile phones than on a computer.
However, I have noticed some mobile web services are less rigorous in their testing. This is generally fine unless your service are directly dealing with real money. For example, EBay's mobile website http://m.ebay.com doesn't have anything to prevent automated brute force account cracking. I guess it wouldn't be too hard to get into xx active accounts in a few hours...