R, 190 178 175 Bytes
Probably still some room for golfing in this. Probably a couple of unnecessary operations in there
l=lapply;s=substring;C=rbind;d=do.call;cat(C(d(C,l(apply(d(C,l(a<-scan(,''),s,1:(w=max(nchar(a))),1:w))[(h=length(a)):1,],2,paste0,collapse=''),s,1:h,1:h))[,h:1],'\n'),sep='')
Ungolfed and explained
a<-scan(,'') # get STDIN
h<-length(a) # number of lines
w=max(nchar(a)) # length of longest line
M<-lapply(a,substring,1:w,1:w) # create a list of split strings with empty chars
M<-do.call(rbind,M)[h:1,] # turn it into a matrix with line order reversed
M<-apply(M,1,paste0,collapse='') # paste together the columns
M<-lapply(M,substring,1:h,1:h) # split them back up
M<-do.call(rbind,M)[,h:1] # reform a matrix
M<-rbind(M,'\n') # add some carriage returns
cat(M,sep='') # output with seperators
Test Run. It is interesting to note that due to the way that scan works, the whole sentence can be input with spaces and still give the output as specified.
> l=lapply;s=substring;C=rbind;d=do.call;cat(C(d(C,l(apply(d(C,l(a<-scan(,''),s,1:(w=max(nchar(a))),1:w))[(h=length(a)):1,],2,paste0,collapse=''),s,1:h,1:h))[,h:1],'\n'),sep='')
1: Programming
2: Puzzles
3: &
4: Code
5: Golf
6:
Read 5 items
P
Prog
&uzz
Coderam
Golflesming
> l=lapply;s=substring;C=rbind;d=do.call;cat(C(d(C,l(apply(d(C,l(a<-scan(,''),s,1:(w=max(nchar(a))),1:w))[(h=length(a)):1,],2,paste0,collapse=''),s,1:h,1:h))[,h:1],'\n'),sep='')
1: Programming Puzzles & Code Golf beta
7:
Read 6 items
P
Prog
&uzz
Code
Golfram
betalesming
>
12Also, will it be one word per line, or can there be spaces? If there are spaces, should they collapse down, or can spaces bear weight? – Glen O – 2015-08-24T04:30:39.763
53"P Prog &uzz Coderam Golflesming", sounds like there's a new candidate for the site's title.. – jcai – 2015-08-24T06:44:54.783
1
Someone's going to use Marbelous (https://github.com/marbelous-lang/marbelous.py) ?
– Charlie – 2015-08-26T20:11:51.7231I decide to use a physics engine and hold a 0 byte – l4m2 – 2018-05-21T07:05:18.183
2Can there be trailing spaces in the output? – Erik the Outgolfer – 2018-06-15T10:23:06.633