Generally speaking we try to maintain a fairly consistent look and feel across the widgets as far as buttons go, but there are definitely avenues which you can use to customize the appearance. To change the color of a button, all you would need to do is set a backgroundColor in the styles property. As far as glassy appearance goes, this is handled by a semi-transparent png. Take a look inside the Themes/ folder in the Framework and you can get ideas on how to customize that.
Enjoy!
-Jeremy