Hi,
yeah, no built in flash but very good high ISO performance with the new sensor. The detachable flash that comes with the camera is only as powerful as a p&s flash so I agree flash is a limitation unless sony comes out with another solution.
I was pretty much set on Panny GF1 until I saw the nex...
Also, Sony is coming out with an A55 which bridges the gap between the nex and traditional dslr.... for me the nex is perfect, I am a p&s upgrader and never felt it was worth it to carry around a full size dslr but the p&s is too limiting and I got bored with it, and it's results. Unfortunately, the nex is very revealing as to how poor my photography skills really are 
Hey!
First off I have to say that's nice to run into a Sony cam user here.... a very rare thing around here.

I think the NEX were aimed at P&S user or someone who want a smaller cam but still most of the flexibility, image Q and control of DSLR. And seem to come out to compete directly with the 4/3 system. With the NEX bigger sensor I think it is a huge advantage there. But I still think Sony should have put a built in flash in it even if it is a small one.
Anyway, yes I saw the A55 listed as "pre-order" on B&H. Definitely a whole new way of cam to me. The translucent mirror is nothing new. I actually have a Bolex H16 Rex5 16mm film movie cam that use this and it is from 1967. The only downside is that you loose 1/3 of the stop of light... but that shouldn't be much of a problem.
The A55 sound greats with full AF for video shooting and etc. Sound like a perfect vacation and all around digicam or most people. As for me... I'm still more of traditional photographer. I still shoot with B&W film something with my old film cams. My A700 still works fine for me but have been drooling over the A900 a bit

No video, no live-view just a nice tool to make photographs with.
Anyway, let me know how the NEX work out for you. Would be nice to hear from a real user in the real world instead of those so called pro reviewers out there.

Take care,
Buddy