Query regarding current state of limitations on PUT and DELETE on real world platforms

[John Panzer <jpanzer@xxxxxxx>]

After having a discussion regarding deployability of AtomPub recently, 
I'm hoping to gather some real world data on what kinds of pain points 
actually exist in 2007 regarding implementing full REST, including PUT 
and DELETE.  I've seen some client libraries that assume that all the 
world's a GET except when it's a POST, but usually the bug fix is 
simple.  This was a major topic of discussion several years back; what's 
the current state of the world?

Specifically, are there server platforms that make it more difficult to 
implement custom PUT & DELETE than custom POST handlers?  (Rails is, I 
understand, improving for example but I don't know the details.) 

Also, are there client platforms or environments where it is simply not 
possible to PUT or DELETE?   (Flash, I'm looking at you, though Flash 8 
is said to fix this.)

And, what's the first derivative -- my sense is that platforms that 
aren't REST compatible are moving in that direction, but I don't use them.

Thanks,
John