I think overall it's a good move because it helps people scan and see if a design catches their eye.
I think I would also include a one line t-shirt title under each design and link it to the product page. That would help both text scanners and search engines find each product page.
The one thing you will need to monitor is if it increases the number of "bounces" from your main page. Meaning, if the additional images increases the page loading time too much (think dialup users), it could make people leave your page before all the images load.
I'm on high speed DSL and the images still took a *bit* long to load. Not so much that I would have left, but if I had a slower connection, I might not have had the patience.
670k of images is a LOT of images to load for a main page. Here's what I got when I ran your page through a page load speed checker:
http://www.websiteoptimization.com/services/analyze/
Download Times*
Connection Rate Download Time
14.4K 523.72 seconds
28.8K 261.96 seconds
33.6K 224.56 seconds
56K 134.82 seconds
ISDN 128K 41.43 seconds
T1 1.44Mbps 3.78 seconds
*Note that these download times are based on the full connection rate for ISDN and T1 connections. Modem connections (56Kbps or less) are corrected by a packet loss factor of 0.7. All download times include delays due to round-trip latency with an average of 0.2 seconds per object. With 117 total objects for this page, that computes to a total lag time due to latency of 23.4 seconds. Note also that this download time calculation does not take into account delays due to XHTML parsing and rendering.
I tested it using the netmechanic free load time tester and this is what I got:
http://r.netmechanic.com/toolbox/summary.cgi?f=f/111/053/1459/29-17066/&s=NetMechanic&fv=5&ft=3
http://r.netmechanic.com/toolbox/load_time.cgi?f=f/111/053/1459/29-17066/&p=1&vi=1&fp=1&fv=5&s=NetMechanic
Load Time rating = 1 172.32 seconds, height/width problems
Load Time by Connection Speed
Connection Speed Download Time
14.4Kbps 344.64 seconds
28.8Kbps 173.32 seconds
56Kbps 89.17 seconds
ISDN (128Kbps) 40.55 seconds
Cable (512 Kbps) 11.64 seconds
T1 (1.44 Mbps) 5.43 seconds
SDSL (1.544 Mbps) 5.20 seconds
ADSL (2.0 Mbps) 4.47 seconds