Ah, well if you are talking about Silver Efex Pro, they also do a "plug-in" for Lightroom that is almost identical to the Aperture version. In each case, while Nik call them "plug-ins" for marketing purposes, these are separate (and sophisticated) programs that are launched from LR/Ap just like you can launch Photoshop.
Lightroom also has Develop presets and templates - you see these in the left panel of Develop. These are like Lightroom recipes and were what I was talking about. There are sites offering hundreds of these and which are happy to take away from you your money and your creativity!
The Julianne Kost videos at Adobe are very good.
John