I'm getting a replacement unit...
 

Sent my tj37 in to sony for repairs and have now learned that I will be receiving a replacment unit...my clie was still in excellent condition and I am not really sure what to expect. Does anyone have any experience with receiving a replacement unit?

What went wrong with your TJ37? Mine is in poor condition and would love a replacement.

The battery discharged completely and after recharging I could no longer use wifi, it would give me a "device error" whenever I tried to access a wireless network. I was following the postings here on this topic and thought Sony could repair it but I guess not.

Got my replacement...looks to be in great condition ( a couple of scuffs around some of the buttons) but not too bad. Since it was a replacement they included everything a new unit would (stylus, install cd, usb cable and little connector thingy...but no battery charger) which is nice because now i've got two of each of those. All in all it wasn't as bad as I thought.

In the last 10 years I believe that everything I have sent in for warranty repairs to any company has resulted in a "replacement unit". (except my car!)
It is much more cost effective to send out a refurbished unit to the customer than it is to diagnose, repair, track, and ship the same item you sent in. Then, if your old one can easily be repaired it goes into the refurb pile for the next person. I have even recieved new replacements a few times, which is apparently the cheapest solution until they build up a stock of refurbs. For what it is worth, it is often hard to tell a refurb from a new unit.