I bought mine a couple of weeks ago than to wait for the iPad 2 in a few months time becuase I could do with using some apps on the iPad now for the next few months than nothing at all. I mean, I really need to have an iPad right away and use apps that would be of big help in my life.
It is up to you to decide to buy now or wait for iPad 2. However consider this...
Who knows? In a couple of years time or thereabouts, maybe there will be iPad 3 coming out? You could always buy iPad now, use it for a few years, then if there is going to be iPad 3, you could get it if they designed it at all. I figure it seem better to get myself iPad now, use it for many years and if there is going to be iPad 3 or ever 4 in a number of years time, upgrade to the newer one, than to wait months for iPad 2.
Beside, what are the chances of the iPad 2 being shipped out on time or being delayed? You never know, you may hope for iPad 2 only to find it being delayed for a few more months.
But it is still up to you.
Beside, as 1994-C1 points out, Apple is not going to change the screen size, and I believe in this, after all one of the iPad's many strong selling points was the big screen. So you can do it either way, buy now and you get a big screen or wait until iPad 2, but you still get a big screen.
It is really a matter of do you think you want to use an iPad now?