Hey hey, just in time for my borthday! Party time for all!
You're not from Europe...
I'm secretly praying that because Europe and Australia are both PAL... the release dates will be relatively close. So yeah, I'm counting my chickens before they hatch. And there are a lot of chickens.
*maskpalm* (c wat i did thar?) PAL is not (as, oddly, many people seem to think) the name of a geographical region. Some people seem to imply that they think that they can (for example), say "OMG I'm taking a vacation/trip to the PAL region!"
PAL stands for Phase Alternating Line(s). It is an analogue television colour encoding system used in broadcast television systems in many countries. Other common analogue television systems are NTSC and SECAM.
Therefore, there's no such thing... as a PAL 3DS game... and therefore, that has nothing to do with whether the Australian release is close to Europe or not.
That being said, here's a list of Australian and European release dates for the last few Mario platformers:
Super Mario Galaxy = November 16, 2007 (Europe) -- November 29, 2007 (Australia) -- Australia was 13 days after Europe
New Super Mario Bros Wii = November 11, 2009 (Australia) -- November 20, 2009 (Europe) -- Europe was 9 days after Australia
Super Mario Galaxy 2 = June 11, 2010 (Europe) -- June 30, 2010 (Australia) -- Australia was 19 days after Europe
Super Mario 3D Land = November 18, 2011 (Europe) -- November 24, 2011 (Australia) -- Australia was 6 days after Europe
BTW, as you may know, Australian releases are generally always on a Wednesday or Thursday.
Therefore, the possible release dates for Australia for NSMB2 are:
August 1/2, August 8/9, August 15/16, August 22/23, and August 29/30.
The most likely dates being either August 15/16, or August 22/23.