have a glance at the article http://searchengineland.com/yahoos-social-plan-twitter-twitter-more-twitter-24215 describes wat all changes Yahoo!! made in the last few months and launched a few search engines... comments pls...
Nonetheless, Twitter will always exist as an opportunity and is not going anywhere. Use it, take advantage of it, or get passed by . . . .
It's easy to bash Twitter as a no-go but I build my lists every day using it properly. If you know what you are doing it works really well. I know there is a lot of spam on there and it's hard to see through the crap but every new app attracts that.