>    I am aware that there are data signals currently being
> sent down containing internet e-mail and other such, but
> replies are STILL limited to terra-link pathways. AFAIK
As far as the general public is concerned, yes.  However,
there are some companies launching low earth orbit (LEO)
sats to provide 2 way data and voice comms using very
small antennas -- suitable for mobile and hand-held
use.
>    If the normal mesh dishes (7-12') could also be used
> for transmitting, the cost for that part would be small.
> Even if it required a solid dish with a deeper parabola,
> it would surely be possible for the homebrew enthusiast
> to construct a functional array with available materials
> and techniques.
You would not be able to build your own since it would
not be Amateur Radio.  Any commercial outfit would have
to provide all the equipment in order to be legal -- you
cannot (legally) build your own cell phone for example :)
>    And the wattage output of most of the "C" xpndrs being
> around 20-30 watts, it doesn't seem like it would be too
> hard to develope at least that much (if not a bit more)
> for purposes of uplink.
Video uplinks generate about 10 times that amount, but narrow
band Ku systems require much less.
> I'd like to discuss the feasability of this idea.
> And if there is already a system like this in operation
> (I've heard of Digital Amateur Packet Sat Gateways),
> I'd like to know more about it.  IE; what would I need
> in the way of hardware to obtain access ?
Why not ask some company to include some Amateur Radio
transponders on their geo-synchronous satellite?
If the price was right, they might do it :)
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