This is what you need to do to start playing around with Twitter from my personal experience:

For your Blackberry you can search using the BB browser and you will find the link to download:

Ubber Twitter: http://ubertwitter.com/ - this is the best application so far for Blackberry. 

For your desktop – this is cool since you can track both FB and Twitter at the same place and it is nice to work with:

http://tweetdeck.com

There are several Twitter Search websites and this is I think it is going to be an interesting thing to keep an eye since it is a real time search engine. I like this one: 

http://www.twazzup.com/

Julio, @ Shanghai today: http://myloc.me/show.php?id=6SJV