So far only Eris, besides Pluto, has been named within the plutoid classification. Eris is larger than Pluto and further away from the Sun that Pluto.

To be classified as a “plutoid” an object must circle the Sun; be smaller than the minimum size for a planet; be not too large so that gravity gives them a near-spherical shape; and be further from the Sun than the planet Neptune.

Specifically, the IAU states, “Plutoids are celestial bodies in orbit around the Sun at a distance greater than that of Neptune that have sufficient mass for their self-gravity to overcome rigid body forces so that they assume a hydrostatic equilibrium (near-spherical) shape, and that have not cleared the neighbourhood around their orbit. Satellites of plutoids are not plutoids themselves, even if they are massive enough that their shape is dictated by self-gravity. The two known and named plutoids are Pluto and Eris. It is expected that more plutoids will be named as science progresses and new discoveries are made.” [IAU press release]

Here are some comments from astronomers after hearing about the news:

“Plutoids or hemorrhoids, whatever they call it. This is irrelevant.” –Dr. Alan Stern, former NASA space sciences chief. [Time]

‘Instead of being a "puny" outer planet, Pluto is now a "prototype of a new type of fascinating objects.’” --Catherine Cesarsky, IAU president [Los Angeles Daily News]

"It [plutoid] doesn't really roll off the tongue very well. Maybe it'll make it." --Mike Brown, the California Institute of Technology astronomer who discovered Eris in 2003. [Times Record News}

"It's going in the right direction. I'd still rather have it just be known as a planet." and "I grew up with nine planets, I'm sorry," Ralph McNutt, a planetary scientist at Johns Hopkins University. [AZCentral]
“We wanted a rather clear name that related to Pluto. “Plutoid fit the bill. And I am happy enough with it. It means Pluto-like.” --Astronomer Brian G. Marsden, secretary of the CSBN (IAU). [Science News (subscription required)]

"The IAU is a democratic organization, thus open to comments and criticism of any kind. Given the history of the issue [Pluto], we will probably never reach a complete consensus." --Karel A. van der Hucht, IAU General Secretary [PhysForum.org]