Australia

Justin Langer

Matthew Hayden

Ricky Ponting

Damien Martyn

Steve Waugh

Michael Hussey

Adam Gilchrist

Shane Warne

Jason Gillespie

Ryan Harris

Glenn McGrath
Australia don't need a 5th bowler or an all rounder. I went with Ryan Harris because I think he was our third best quick of the 21st century he was just injured way too much. He would excel bowling with Warne and McGrath keeping the pressure on. There's a case that maybe he is too similar to McGrath and that Lee or Johnson provide the extra pace dimension. He actually played 51 internationals for Australia so he just makes the cut but that was stretched over a 6 year period it was only a frail body that kept that down. Mitchell Johnson and Brett Lee could be erratic at times, especially Mitchell Johnson, but they could be worth the risk with such a safe bowling attack. Personal preference here. It does mean the tail is a little long without Lee or Johnson.
Damien Martyn over Michael Clarke was hard but Damien Martyn's record in the 2000's matches up closely to Michael Clarke's and he did better away from home although failing in Bangladesh is what really brings down Michael Clarke's away record and for whatever reason Michael Clarke couldn't bat at 4. Darren Lehmann in consideration somewhere too, possibly for an Australia 'A' side.
Steve Waugh gets in because he is a legend and he ended up batting higher than his test and ODI averages in the 2000's and really he was playing good enough to have at least gone on the Indian tour. There could be a case for removing him and playing Andrew Symonds but I don't feel the team needs an all rounder with the bowling attack it has or you could remove Justin Langer and open with Adam Gilchrist and slot in either Andrew Symonds as an all rounder or Michael Clarke as the extra batsman who could bowl if needed.
About 7 out of the 11 of an Australian 21st century team picks itself with Hayden, Ponting, Hussey, Gilchrist, Warne, Gillespie and McGrath going to be in the team so it comes down to filling in the holes in the team.
Australia 'A'

Simon Katich

David Warner

Steve Smith

Darren Lehmann

Michael Clarke

Brad Haddin

Mitchell Johnson

Brett Lee

Brad Hogg

Stuart Clark

Stuart MacGill
Something a little different and for a bit of fun. I went with 5 bowlers and 2 spinners. I still couldn't find room for Andrew Symonds so maybe depending on the pitch you could remove Brad Hogg and put Andrew Symonds in to the team.
Open the bowling with Clark and then have Lee and Johnson alternating short and sharp fast spells with 2 spinners keeping the quicks fresh. You would probably have Clark in tandem with a spinner for a while then replace with Lee and then Johnson at the one end while the spinner is at the other, it would be pretty relentless so hopefully Lee, Johnson and MacGill aren't leaking runs.