I just wrote an article about the replacement when Wooglin(sp?) did his belt. I've seen enough 3.4L water pumps leak to recommend it be changed. It uses Form-In-Place-Gasket (FIPG at the dealer) even though you may remove a paper gasket. The article will be available May 1st.

Send your VIN to a couple of online Toyota dealers and you should find a 30% savings off of list price.

Here's a story:
When I found the water pump leaking on our 4Runner and it was still under warranty (with only 50,000 miles), I took it to the dealer.
The service advisor called to say the timing belt was a little frayed and the drive belts should be replaced.
Since it was all apart, he could offer me a special deal to install these belts without a labor charge.
The low, low price was $225.
You can probably guess that I declined.
<img src="/forums/images/graemlins/lol.gif" alt="" /> <img src="/forums/images/graemlins/lol.gif" alt="" /> <img src="/forums/images/graemlins/lol.gif" alt="" /> <img src="/forums/images/graemlins/lol.gif" alt="" /> <img src="/forums/images/graemlins/lol.gif" alt="" />
I think these would be about $80 (delivered) from an online dealer.