I have stated in a previous post that I wasn't ever going to review stuff on this blog, but I find that I can't help myself. What I can do is limit the number of words I use.
I got a pair of Ortlieb front roller classics (that I use on the rear rack, because I didn't want or need great big panniers) a few months ago.
These bags are not only worth their high price tag, but are even worth braving the perils of cycling forum research and international shopping. I have ridden in some very heavy rain on several occasions with these, and they remained bone-dry inside. They are waterproof. They are one of the best cycling related investments I have ever made. End of review. Should my opinion change over time, I'll let you know.
Update - October 2010 - These panniers are holding up really well... used every day for my work commute. They didn't see too much rain over the summer, but when used in the wet this Fall they've continued to remain totally dry inside. I'm not too crazy about the "pull down" strap... I don't like adjusting it and have almost lost those straps a couple of times now. I'm thinking about a hack for those that should work nicely... anyway, I still love these panniers over a year later.
Remember, if Brevity is Golden, then Silence is Wit...