Change.org has an online petition urging carriers to expedite donations given to Japan earthquake relief, which is what they did after the Haiti quake. As of right now, it's become apparent that donations given to Japan are taking 30-90 days to get processed.
This isn't to say that iTunes donations or any others are getting to organizations helping with the relief effort any quicker, but something about 30-90 days sounds wrong.
mGive Foundation on the delays, as quoted by change.org:
How long does it take for my charity to receive the funds?
In response to the Haiti Relief Effort, carriers are remitting donations immediately to nonprofit organizations. Generally, the typical time frame for remittance is based upon the billing cycles of the donors and can take, on average, 90 days from time of donation for the charity to receive the funds.