First I had problems refreshing my timeline in Tweetbot. Twitter.com (home page) was giving 'Something is technically wrong', but my profile page would load.
I couldn't tweet from there but tried again and it worked... but now I'm not able to get anywhere via web or apps.
Same here - Sacramento, CA
Same from Dallas. The landing page is up, but when you try to view tweets you get the error.
Same from India, the status page [1] is holding it up though, saying "All systems operational. Updated a few seconds ago".