Of course they expected a high demand for the new version, and doubled the bandwidth in preparation . But according to Denis Roy so many people have been trying to download Eclipse 3.1 that the whole site has been crippled. I'm sure the article on slashdot didn't help. He writes:

Even doubling our available bandwidth couldn't save us from the popularity of Eclipse. Although the new hardware is holding up just fine, we are simply overwhelmed by the amount of requests. We were saturated at 2,200 concurrent connections, and we are currently at 4,320 - and have been at that rate for the last 8 hours.

The webmasters are working on setting up a high capacity mirror site on a separate Internet link so they can redirect download traffic to it. Until then everyone is urged to either postphone downloading, find a friend with a copy, or use one of the existing mirrors if you can make it in to the download page. When the smoke clears they'll propose ways to avoid this problem for future releases (send your ideas to webmaster at eclipse dot org). Despite the problems, so far 3.1 has already reached 95,000 downloads in the last 18 hours.