Your phone is in what's known as "recovery mode", all you need to do is; on your computer download "tinyumbrella" from
http://blog.firmwareumbrella.com/ (links are on the left). run the program, plug in your phone and then click on "exit recovery mode" and you should be good.
EDIT;
There's a link on that site that says "fix recovery (OS)", i've never heard of that, but i know my method works, so use my way.