I have loaded the Spring 2.5 documentation onto my Amazon Kindle and want to share my experience of this. First I emailed the pdf version to my Kindle, which Amazon automatically converted and installed on my Kindle through the free Sprint EVDO Broadband wireless connection. I would not recommend doing that however because it's a real pain trying to navigate through a big pdf on the Kindle.
Then I zipped the directory containing the 2.5 documentation in html format ("html_single") into a zip file and emailed that zip file to my Amazon Kindle. The results are spectacular. All the internal html links work correctly. Html format is definitely the best way to keep Spring documentation on your Kindle.
I think word about the Amazon Kindle will be spreading as more people get theirs in the mail. It might be worth considering a Spring project to build web applications, etc., that render nicely on the Kindle.