I had this nice long post about this problem, but hit the wrong key and accidentally opened up my bookmarks, and lost the entire post, so here's the short story:
If you're having problems (like I was) getting decent prints from Lightroom 2 to an Epson R1800, try this: download the European Epson driver. I saw that solution posted on the Adobe forums, and I couldn't believe it worked, but it did!
Previously, all my photos were coming out extremely dark, and after tons of ink, paper, time, and effort wasted trying to fix this, I was ready to list the printer on Craigslist to sell. Once I downloaded and installed the European driver, I seem to be back in business!