Yes, small caps, especially international small caps, have had a recent runup, there is no debate there. However, I included them anyway as part of my long-term asset allocation plan. For me, that is 5% small/micro caps, which I split between USA and international. Some say getting in now would be performance chasing and too late, as you could very easily underperform for a few years, but I don't see anything wrong with this strategy if you are willing to stick with a plan and rebalance as necessary.

 As a side note, in the Diehards forum, there was quite a bit of discussion on international small caps. The feeling was that the correlation with USA was lower with international small caps than with international large caps, as the smaller and more localized companies were less tied to USA large caps. So, there may be a diversification benefit here.

Dan