Bingo - that was the little nudge I needed, now I have success:
Botanicalls v2.21
POST /1/statuses/update.xml HTTP/1.1
Host:
api.supertweet.net
Authorization: Basic [secret]
Content-Type: application/x-www-form-urlencoded
Content-Length: 28
status=Current Moisture: 0p.
HTTP/1.1 200 OK
Content-Type: text/xml; charset=ISO-8859-1
Date: Fri, 25 Jun 2010 15:29:22 GMT
Vary: Accept-Charset, Accept-Encoding, Accept-Language, Accept
Accept-Ranges: bytes
Server: Restlet-Framework/2.0snapshot
Content-Length: 2154
The only thing that fails now it that it chokes if I send a "%" as
part of the status, need to html-ize that probably...