x <- 1:2; dim(x) <- 2? A vector or not?

Ran into the follow intermediate case in an external package (w/
recent R v2.8.1 patched and R v2.9.0 devel):

x <- 1:2
dim(x) <- 2
dim(x)

[1] 2

x

[1] 1 2

str(x)

int [, 1:2] 1 2

nrow(x)

[1] 2

ncol(x)

[1] NA

is.vector(x)

[1] FALSE

is.matrix(x)

[1] FALSE

is.array(x)

[1] TRUE

x[1]

[1] 1

x[,1]

Error in x[, 1] : incorrect number of dimensions

x[1,]

Error in x[1, ] : incorrect number of dimensions

Is str() treating single-dimension arrays incorrectly?

What does it mean to have a single dimension this way?  Should it
equal a vector?  I am aware of "is.vector returns FALSE if x has any
attributes except names".

/Henrik