Redirects on your homepage are bad, they are just plain rude -- to visitors, to other webmasters, and to search engines.
Two examples of sites using redirects on their homepages are: eFunda and the IEEE. At least the ACM knows better! These are two of the largest and most important engineering sites on the web and they are just being lazy. Don't get me wrong, lazy can be powerful, but this isn't one of those times. In these cases, lazy is just plain sloppy.
What is the purpose of having http://www.efunda.com/ redirect to http://www.efunda.com/homepage.cfm? C'mon guys, configure your webserver! This is simple to fix. The IEEEs redirect looks like it is using some kind of portal software. Again, fix your config.
Why am I so worked up? Redirects on your homepage are just plain rude. A 3xx level response indicates a redirection. Specifically, the 302 response these sites use is a temporary re-direct. From the specification, "Since the redirection might be altered on occasion, the client SHOULD continue to use the Request-URI for future requests." This is like putting a sticky note on your door saying, "I'm in Olin 110 -- go downstairs, around the corner and knock on the door." You can't count on the person being in the same place, so you have to go check their door again first and read another note. Here is my bottom line: Be polite, meet your guests at the door, and maybe even offer them a cold one.
Thankfully, most search engines can traverse these pointers, but it wasn't always the case and you never know. After all, not everyone gets taught pointers.