Doing a feature on someone without asking them is more of a missed opportunity than a "faux pa" (sp) IMHO. I'd like to link back to a person when they do a feature on me and exchange the favor in some cases. I'd also like to make sure my name is spelled right and stuff... once someone linked to me and didn't even link to my blog or SCS'er gallery even which I thought was just odd.
Blogs that are successful function based on multiple link backs. Linking helps show your blog is active and "life". Ths also heps search engines find you. That's why a blog is different than a website; it's based on social marketing... it's the reason "YOU" were the Time Magazine person of the year!
Here is a great article about blogging successfully I just found the other day...