What is the maximum optical zoom on a compact digital camera?

Is there a physical limitation on how powerful it can be?

It all counts on lenses. From what I've learned, Sony has a great 5X in it's new T-series.
Casio has a 7X in it's lineup, but it's pictures leave alot to be desired.
New technologies are coming out all of the time. I'm sure we'll see 10X soon enough.
BTW...by compact, I mean compact, and not just point and shoot.

I'm not an authority on this, but my friend who's into photography was talking about it.

The best for zoom is on the cameras which have separate lenses (Mostly professional quality) Then you have what ever the limits there are to the lenses ...

As far as being able to zoom in after taking a picture, it depends on the quality of the picture you took. Most of the times, this is limited by the pixels - it will get too blurry when you close up too much.

10x

no limit other than sensible physical size and expense.on a compact 10/12 x is quite common