Painting glassware and barware (wine glasses, in particular) is a very popular trend in crafting. There's a large display in our local Michaels.
I have been using Pebeo Vitrea 160, which is manufactured by a french company and marketed here. They also make a porcelain paint for dishes.
Why am I using this paint? It is made for glass, and is dishwasher safe after the glass has been heated in the oven at 325 degrees F. (which is 160 C.)
I made wineglasses yesterday for a family birthday - the stem of the glass was the tree trunk, the bottom of the glass had my DH parent's names and the date, and up in the bowl of the glass were every family member's name and leaves. It was a family tree glass. Isn't that great?
Anyway, everybody loved their glass and took one home. Thank goodness Pier One is having a big sale on glasses, so they were cheap.
For inspiration of what might be possible, here is the website of a lady who is in the Tampa area that makes custom hand painted glassware. She sure inspired me!
http://www.jabberwalkie.com/ocean_series.htm
Of course, my glass used SU! leaves and acorns!
Nina T.