A good starting point to gather information is to subscribe to the wear-hard@haven.org mailing list, you have to send a message with the word subscribe in the subject to wear-hard-request@haven.org.
The archive of this mailing list is mirrored at Wearable Central This site was founded to be an archive center for the mailing list and the newsgroup. It is maintened by R. Paul McCarty.
You can also read one of the very good FAQs such as the wearcompfaq or you may go to the wearable webring ( at the time of this writting the webring lists 35 sites ).
You can find information on the web sites of the company cited in the various sections of this document and as stated earlier in this document : The companies quoted here are just for your information only, I do not endorse any of their product, this just in order to help you.
Some science fiction books can be a good introduction to Wearable computing. Among other books one can think of ( alphabetical listing ):