How can I post my location on Facebook or other sites, from Android, while linking to OSM ?

You have two separate problems :

• Publishing your position from Android
• Displaying a position on an OpenStreetMap background

The second one is easily answered using Openlayers. If you feel enthusiastic, you can even write a little Facebook application based on that !

The first one can be answered by scraping Latitude's data on your Google Latitude "badge". I wrote a little script for that which I run from Cron :

#!/bin/bash
# latitudelogger.sh
# Logs Google Latitude positions
#
# Author :
# Jean-Marc Liotier <jm@liotier.org>
#
# Changelog :
# 20090604 - 0.1 - Initial release, based on latitude2brighkite.sh
#
# Requirements beyond Bash :
# - The Perl JSON library (http://search.cpan.org/dist/JSON/)
# (available in Debian as libjson-perl)
# - Curl
#
# Known bugs and limitations :
# - Requires your Google Public Location Badge to be enabled and to show the
# best available location. For this script to work, your location has to be
# public.
#
# This script is an ugly mongrel hack. I'm an aged script kiddie.
#
# It proves that it can be done, it works for me, and the official Google
# Latitude API will hopefully soon make it obsolete !
#
# The right way to do it would be to parse Latitude's JSON output cleanly using
# the Perl library. But that dirty prototype took me all of ten minutes to set
# up, and it works...
#
# This program is free software: you can redistribute it and/or modify it under
# the terms of the GNU Affero General Public License as published by the Free
# Software Foundation, either version 3 of the License, or (at your option) any
# later version.

# Parameters
#
# Replace this Google Public Location Badge URL with your own
# (choose the JSON one !)
badge="http://www.google.com/latitude/apps/badge/api?user=7832225593622256926&type=json"
#
# Working directory for temporary files
workdir=/home/jim/applications/latitudelogger
#
# End of parameters

date=`date -u +%s`
coordinates=`wget -qO- "$badge" | perl -0007 -MJSON -ne 'print to_json(from_json($_, {allow_nonref=>1}), {pretty=>1})' | grep -A 2 coordinates | grep -v coordinates | sed s/,//`
echo $date $coordinates >> $workdir/latitudelog

There are several options besides Maverick:

1- www.opentouchmap.org from your Android's browser. It will detect your location and "share" it with the integrated sharing service of Android. You can mail it to an e-mail, facebook account, twitter, etc. etc.

2.- gvSIG mini is an navigation app. Long-touch the screen and you'll see a "share" icon to send the link of your location with a OSM map link. It also uses www.opentouchmap.org

3.- OSMAndroid. Lets you to create an OpenStreetBug to ask people to improve the map at that point.

There's a Perl module too: http://cpan.uwinnipeg.ca/dist/Geo-Google-Latitude - again, this is coder stuff. It'd be neat if someone could do the brainwork so we plebs can bask in our stalkable OSM goodness.