Is there a list of which features were added to specific releases (versions) of Bash?

Here are some links to official Bash documentation:

A more extensive list than the one below can be found at http://wiki.bash-hackers.org/scripting/bashchanges

Notable changes in the upcoming bash version

Feature

Added in version

loadable builtin deployment infrastructure

4.4-beta

mapfile -d

4.4-alpha

--help for builtins

4.4-alpha

${var@spec}

4.4-alpha

local -

4.4-alpha

$! and wait for process substitutions

4.4-alpha

Notable changes in released bash versions

Feature

Added in version

wait -n

4.3 (2014)

test -R

4.3 (2014)

declare/typeset -n and associated changes to ${!ref} and for..in

4.3 (2014)

array[-idx] (in assignments, read, unset, etc)

4.3 (2014)

\uXXXX and \UXXXXXXXX

4.2 (2011)

declare -g

4.2 (2011)

test -v

4.2 (2011)

printf %(fmt)T

4.2 (2011)

${array[-idx]} and ${var:start:-len}

4.2 (2011)

lastpipe (shopt)

4.2 (2011)

read -N

4.1 (2010)

{var}> or {var}< etc. (FD variable assignment)

4.1 (2010)

syslog history (compile option)

4.1 (2010)

BASH_XTRACEFD

4.1 (2010)

;& and ;;& fall-throughs for case

4.0 (2009)

associative arrays

4.0 (2009)

&>> and |&

4.0 (2009)

command_not_found_handle (function)

4.0 (2009)

coproc (keyword)

4.0 (2009)

globstar (shopt)

4.0 (2009)

mapfile/readarray (builtin)

4.0 (2009)

${var,[,]} and ${var^[^]}

4.0 (2009)

{009..012} (leading zeros in brace expansions)

4.0 (2009)

{x..y..incr}

4.0 (2009)

read -t 0

4.0 (2009)

read -i

4.0 (2009)

x+=string array+=(string)

3.1 (2005)

printf -v var

3.1 (2005)

nocasematch (shopt)

3.1 (2005)

{x..y}

3.0 (2004)

${!array[@]}

3.0 (2004)

[[ =~

3.0 (2004)

printf %q produces $'...'

2.05b (2002)

<<<

2.05b (2002)

i++

2.04 (2000)

for ((;;))

2.04 (2000)

/dev/fd/N, /dev/tcp/host/port, etc.

2.04 (2000)

read -t, -n, -d and -s

2.04 (2000)

a=(*.txt) file expansion

2.03 (1999)

extglob (shopt)

2.02 (1998)

[[

2.02 (1998)

printf (builtin)

2.02 (1998)

$(< filename)

2.02 (1998)

** (exponentiation)

2.02 (1998)

\xNNN

2.02 (1998)

(( ))

2.0 (1996)

arrays

2.0 (1996)

$'...' (new quoting syntax)

2.0 (1996)

List of bash releases and other notable events

Release

Date

Shellshock patches are released for bash-2.05b through bash-4.3

2014-09-24 to 2014-10-05

bash-4.3

2014-02-27

bash-4.2

2011-02-14

bash-4.1

2010-01-02

bash-4.0

2009-02-23

bash-3.2

2006-10-12

bash-3.1

2005-12-09

bash-3.0

2004-07-27

bash-2.05b

2002-07-17

bash-2.05a

2001-11-15

bash-2.05

2001-04-09

bash-2.04

http://ftp.gnu.org/gnu/bash puts it around 2000-03-21

bash-2.03

1999-02-19

bash-2.02

1998-04-20

bash-2.01

1997-06-06

bash-2.0

1996-12-23

bash-1.14

1994-06-02

bash-1.13

1993-09-03

Looks like Chet Ramey takes over as maintainer between 1.12 and 1.13

bash-1.12

1992-01-26

bash-1.11

1992-01-10

bash-1.10

First mention found at 1991-10-07, so some time before that

bash-1.09

First mention found at 1991-06-02

bash-1.08

1991-05-22

bash-1.07

likely 1991-02-01

bash-1.06

 This is a tough one. There was apparently a "bootleg" version of 1.06, so this requires more digging

bash-1.05

1990-03-03

bash-1.04

First mention found at 1989-11-07

bash-1.03

1989-09-02

bash-1.02

First mention found at 1989-07-09

bash-1.01

1989-06-23

bash-1.00

Hard to search for ...

bash-0.99

First mention found at 1989-06-11