Using dplyr's rename() including variable names not in data set

Completely ignoring your actual request on how to do this with dplyr, I would like suggest a different approach using a lookup table:

sample1 <- data.frame(A=1:10, B=letters[1:10])
sample2 <- data.frame(B=11:20, C=letters[11:20])

rename_map <- c("A"="var1",
                "B"="var2",
                "C"="var3")

names(sample1) <- rename_map[names(sample1)]
str(sample1)

names(sample2) <- rename_map[names(sample2)]
str(sample2)

Fundamentally the algorithm is simple:

1. Build a lookup table of current variable names to desired names
2. Using the names() function, do a lookup into the map with the mapping indexes and assign those mapped variables to the appropriate columns.

EDIT: As per Hadley's suggestion, I used a named vector instead of a list, makes life much easier. I always forget about named vectors :(