[snip]
As we've told you several times, we've made a deliberate trade-off choice.
1) The sitenotice is **not required** to use or operate the site; it's an extra. As such, not seeing it in an unsupported browser doesn't interfere with your ability to use the site -- this is called "graceful degradation" and is a web best practice.
2) Using JavaScript includes to maintain the notice avoids problems with caching and search engines indexing a temporary notice text for a long period.
So far this is the best way to provide a dynamic notice to the majority of our visitors without causing problems for others. If you have technical suggestions for alternate implementations, they're welcome in a more relevant channel such as wikitech-l.
-- brion vibber (brion @ wikimedia.org) CTO, Wikimedia Foundation San Francisco