If the purpose of the work is a book and presenting it to publishers - then overmatting, etc. is a bit of a waste of $'s. Loose prints in mylar sleeves in a portfolio box is a much more exceptable presentation. It allows the designer/publisher free access to all the images and allows them to begin to see how the images would work together in various sequences. It allows them to be able to xerox the images for possable page sizing and layout ideas. The perfered size for this purpose is 11 x 14 as it also gives them a idea if certain images will "holdup" at say a doulble page spread.
Even some gallerys would rather have loose prints presented in clear mylar sleeves, (the reason you sometimes get back your matts and prints in seperate piles) which allows them to layout the work to see how the images play one against the other.
As for some of the previous suggestions for gallery submissions - Its been my experience that most people that submit work to gallerys "overdo" their initial presentation and make it more difficult to be viewed than is necessary. Try putting yourself in the gallery directors place (who has a limited amount of time set aside each week to view new work) - you receive a portfolio that has been presented (as one mentioned) matted, mounted, with interleaving tissue and in poly sleeves. To begin to even start looking at the work you have to "unpack" each individual print and then when finished repack. The gallery can picture how the work will look matted - its their job. Even including gloves is a bit over the top unless you are sending the work to a place that you assume does not know how to properly handle work.