Question: Are the owners details retained in a picture?

I mean, when I click a pic with my web-cam and check the properties, I find that the owner's (my) name is present in it.

When I upload the same to an image hosting site or lets say in a forum, is any such information (apart from what is seen from the picture itself) retained in the picture?

Answer: 
Not all metadata you see in the Windows "File properties" window is *inside* the file... In particular, such things as "Owner" and "Date modified" **are not** transferred over the web when uploading the file.
The metadata is part of the image and follows the image wherever it goes, unless the online service strips this information (unlikely). However, it is possible to strip the metadata off an image before uploading it using either general purpose image manipulation software or specialized image-metadata software.