Nanorobotics is an emerging field that deals with the controlled manipulation of objects with nanometer-scale dimensions. In addition, initial uses of nanorobots in health care are likely to emerge within the next ten years with potentially broad biomedical applications.
Concerning the second part of your question, read these two articles.
http://www.uptuplus.com/index.php?/computer-seminar-topic/20081031548/nanorobotics.html
http://www.newswiretoday.com/news/46769/