You can, but then you'll have to reapply next year and compete with those students. Apply this year as well, just defer the place and if you change your mind about your choice then you can try again in 2011.
I would take Russ' advice. It doesn't cost much to apply this year and if you get a spot this year and defer, then you have the reassurance that if you don't get into the course you want next year, you've still got the deferred spot as a backup.
In terms of whether or not there are disadvantages: not really. The only thing if you apply in 2011 is that you will be classified as a
non year 12. However, since your highest educational history is the completion of VCE, then selection officers can really only use your ATAR for basis of determining entry. I guess the only disadvantage is a personal disadvantage - you want be starting uni in 2011, rather 2012.