Ask HN: What is the Hottest New DB Architecture?

Currently we are a LAMP house that exists in the AWS cloud. We use EC2 and RDS to support our infrastructure. Next year we will be in the scaling mood. What db architecture should we be looking at that minimize the porting of our app.

We are looking at hadoop, nosql, mongodb and a few others. Love for any db engineers who've worked on sites with 10,000+ simultaneous connections to give their two cents.

Thanks!