Harrar is an amazing place, it's like a biblical desert. It is the most forbidding place I have ever seen coffee grown. The sun is so strong and the environment so dry, however, that it is the perfect place to execute the dry ("natural") process. The coffee is grown on tiny family plots, picked, dried either on mats or on the ground in the sun, and then the dry fruit (now brittle like a husk) is removed, usually using a giant wooden mortar-and-pestle or a hand-cranked husking machine.
The best dry-processed Harrars have strong blueberry notes, it is true. Interestingly, though, this is not at all consistent lot-to-lot. Since there are few if any large farms in Harrar, and since most small farmers sell to either co-ops or exporters (like Mohammed Ogsadey and his "Horse" operation) you can never taste the product of a single farm or producers, they're always mixes of some kind.
When I say they're not consistent lot to lot, I mean: you might taste 20 lots from a co-op and only 3 might exhibit the blueberry characteristic. It is not perfectly clear where this characteristic comes from; whether it is due to variety, process, soil, or some combination of the three. One interesting thing: the variety grown in Harrar is definitely unique. Also, the coffees grown in east Harrar are said to be more blueberry like than in west Harrar. Every year that I have been tasting coffee, there are at least some Harrars that exhibit this characteristic, so I don't think it has much to do with the "year". It has everything to do with what lot you were able to score. Certain roasters trade Harrar lot numbers like secret codes. There is intense competition to try and find great ones. And it's not easy, let me tell you. This is one of the challenging parts of coffee buying: if you want to buy a really blueberry harrar, you taste stuff as it is becoming available. If you wait too long, you may miss out on one you passed on earlier. If you buy too early, you may miss out on a coffee that becomes available later. If you make a "forward contract" with a reputable supplier, you might not get the blueberries so intensely. It is an art, not a science.
Also, over the course of the year, the blueberry characteristic starts to fade and is sometimes replaced with a horse-manure aroma. This can happen with coffees that have a strong blueberry note in the beginning of the year. For this reason, many roasters are scared of the blueberry, and tend to buy only gently blueberry-y coffees. These coffees, as they age, just tend to get less and less fruity.
We're just at the start of Dry Process Harrar season, so you can start looking for these coffees from your favorite roasters over the next few months. The strongest blueberry flavors will show now through fall.
I've found a few nice blueberry lots this year, although we have to wait for them to actually arrive in the port to have any real idea of what they are like. As a coffee roaster, I always want to have the most intense blueberry Harrar I can find, because I believe that "Eureka" moment is so valuable.
As for other coffees from other places, none really have that distinct blueberry. I usually describe Dry Process Sidamos (including DP Yirgacheffes) as strawberry-like, although I have been known to describe some as raspberry like. Frequently, Yemens have some similar characteristics. I agree with Tim that the fruit is often accompanied by a note of pastry. Last but not least, I think that great Kenyas sometimes have a dark fruit approximating raspberry.
Hope I have been of some help, this is one of my favorite subjects. Great question, Jay.
Specialty Coffee Association of America