One of the biggest questions is how do you get the tea in the beer? I'm very interested in putting tea into beer myself, but haven't been able to do much experimentation yet; my first attempt - a ~30 IBU pale ale with some biscuit, some C60, and aged pu-er tea added either pre-primary (cold-steeped), post-primary (cold-steeped), or post-primary (dry hopped) in three different splits - demonstrated no noticeable tea flavor against the control batch with no tea.
My next attempt is going to be light in color, low in alcohol, and sub-15 IBUs, with a greater amount of tea. If I use pu-er again I'll probably do a 20 minute whirlpool addition since it likes to be brewed near boiling temperatures, while green tea would probably go into the mash.
There are a couple threads floating around about "arnold palmer" beers - an easy-drinking beer with black tea, lemon, and a hint of sweetness. You might want to look those and other tea beer threads up here to see the best methods for getting tea flavor into beer.