Swim improvement!

I grew up swimming so, after avoiding swimming during the first few years of my triathlon experience, when I finally decided to put more emphasis on the swim training, I had a rude awakening to how much speed I had lost. In my first few Ironmans, I swam under 1 hour, which made me feel like everything was under control. But when I would do sprint and Olympic distance racing, well, I'd come out a few minutes behind the leader and where I would have been back in high school. How can my 22 year old self be slower than my 16 year old self?
And though my swim time has worked out decently well, my bike has historically been a weakness, so any if I can make my swim faster, that can only help.
I finally got a good measurement of improvement over the last few months. Back in December, I swam a 500 y time trial in 6:25. Today I swam 2x500 with :30 in 6:19 and 6:21 at a decently lower rate of perceived effort (maybe 70-80% instead of TT pace.) I'll definitely take that confidence booster a month out from the first ironman of 2013!