Distributed Queues, Pub/Sub, Gossip just a few that come to mind.
In your example, you are using what is called a classical three-tier web architecture - a Load Balancer + Stateless Nodes + Scalable Storage. The most interesting part of HA setup in a three-tier web architecture is HA setup of the persistent storage component. It looks like you actually haven't figured that out that piece yet and are waiting for a vendor (Microsoft) to solve this for you.
You can improve availability of your persistent storage (MSSQL) in several simple (or not so simple ways):
1. Use a SQL proxy load balancer (or a cluster setup) - a similar load balancer HA pattern you are already using
2. Shard. You will scale writes and significantly reduce the probably of your system becoming completely unavailable.
In my experience, failure can be detected in seconds and switched over. Adding a reverse ARP setup to share a virtual IP for the clustering servers, the clients won't even have to talk to a different IP in the case of failover. The only case the clients need to handle is to retry upon failed connection, which they should have handled to deal with the occasional network failure.
Grown-up vendors have had this solved for decades, literally. E.g. http://en.wikipedia.org/wiki/IBM_Parallel_Sysplex
PostgreSQL: Comparison of Different Solutions http://www.postgresql.org/docs/current/static/different-repl...
as well as the rest of chapter 25..
That being said, I'm 100% in agreement with you that the two options you supplied would be wonderful additions to our environment.
The tricky part when it comes to CI often occurs in the area of test automation, archiving the builds, building for different environment (UAT, STAGE, DEV, PROD), and to deploy it immediately after build (definitely hard if it involves database and migration).
Some CIs handle archiving the builds (Atlassian Bamboo comes to mind).
Some build system handles multiple builds for different configurations fairly straightforward and easy (Maven Profiles, Rails to some extend)
Automated-deployment is still a bit tricky to setup.
Certain category of test-automation is hard to do in CI (typically around JS, UI code, and functional testing). This particular area requires high-level of discipline from the development team. This is one of the reasons why some teams/companies prefer to use GWT instead of pure JS due to the known best practices and the work-around for "headless" front-end testing (or at least that was the case in the past, maybe the JS testing landscape has changed ever since).
Instead of doing it in a centralized/db manner, Beaker allows sessions to be distributed client side:
http://techspot.zzzeek.org/2011/10/01/thoughts-on-beaker/
It was one of the best things I learned last year.
