A Series 2 TiVo is the second generation TiVo. They have more processing power, USB interface and can run a lot more applications making them more attractive. The logical question you may be asking is: "Can a Series 2 TiVo be made to work here?". In theory yes. BUT (and that is a big BUT) at this time Series 2 cannot play back PAL so unless you are REALLY adventurous and want to do a lot of heavy experimentation the simple answer is do not buy a Series 2.
A common question is: "When will Series 2 work in Australia?". The answer is when someone works out how to make the Broadcom chipset work in PAL mode. "How long is a piece of string?" in other words. Do not ask me I do not know. If you happen to know someone who has access to the programming literature on the Broadcom BCM7020 and BCM7040 chips then kindly pass them on - anonymously if you like.
There are some people successfully running Series 2 TiVo's in Australia by inputting an NTSC signal and outputting in NTSC to a multi-standard TV but I have not attempted this so please do not ask me how. For more information on what can and cannot be expected with Series 2 in Australia and the level of modifications required to get one "sort of" operational please look HERE.
Note in that above link especially the following text about what is and is not suitable:
"1. Buy an S2 tivo off ebay. Do not get anything with a model number begining with 5 as these are the new 2.5 series tivos and haven't been hacked. Anything begining with a 1 has a 110/240V power supply. Anything begining with a 2 has a small 110V power supply and so you'll need to buy a stepdown transformer, and this model can also can be a problem if you plan on using twin drives"