Sort of reminds me of the ole' Herbalife "Lose Weight Now Ask Me How" bit. Curiosity did more than kill the cat, it made him part with his money as well...
I design Twitter backgrounds for clients ( see ours at http://www.twitter.com/SocialMtgExpert ) and although it wasnt that impactful that the tabs were takes away. However...
SEARCH it's now buried when before I used to be able to search names from the top of the page very easily. Instead as one Twitter member suggested maybe they should reinstate the tabs, use the sidebar instead for AJAX-based rolling updates of summize/twitter searches. That would make it an active web interface.