I have recently started collecting raku and, like a lot of other posters on this thread, had the same concerns about lead. However, after a very enlightening and informative conversation with Brian at 2000cranes.com, I've concluded that this is really a non-issue, and I'm now waiting for my second acquisition - a beautiful lead-glazed aka raku chawan.
There seems to be quite a lot of confusion out there, so I thought I'd made this contribution. I'd like to make it clear that I'm talking about Japanese raku bowls, including Raku bowls (capital R) made by the Raku dynasty of Kyoto potters. American "raku" has strayed so far from its Japanese roots that I don't consider it worth mentioning.
First, almost all Japanese raku tea bowls have trace amounts of lead in the glaze. That's because raku bowls are fired at low temperatures for only a few minutes, and lead helps the glaze form properly. Both red (aka) and kuro (black) raku bowls contain lead.
Second, lead has been used in raku glazes for centuries, and contemporary Japanese potters today are well aware of the dangers of lead. So why continue using it? There are many reasons (keeping with tradition, glazing effects, etc.) but the main reason is because raku tea bowls (chawan) are used solely for serving powdered green tea, or matcha. When used to serve matcha, lead-glazed raku bowls are safe.
Third, wine, fruit juice, or vinegar-dressed food has the potential to release the lead in the glaze, so such things should not be put in a raku tea bowl. The assumption that chawan are used only for serving matcha is the reason why the "lead in raku issue" is really a non-issue in Japan. Why would anyone buy a chawan for drinking wine? The assumption is that people have more sense than that.
Fourth, because there will always be wild cards out there who'll use a raku bowl in ways which it was never intended (the same type who put poodles in microwaves), the Japanese Health Ministry has published guidelines concerning raku and lead glazing. In short, it requires that artists working with lead glazes advise their customers about the proper use of the bowl.
If you have a raku bowl and you're using it for matcha, don't worry. When used properly, it's no more dangerous than leaded crystal. And how many households have that on their table?