Credit to pastebin for some code snippets.

Hope this saves someone some time and effort.

#!/usr/bin/python
'''vcard.py - Update your XMPP vcard photo with the image you provide

Usage: vcard.py image_file jid password
'''

from xmpp import JID, Client, Iq, Presence, NS_VERSION, NS_VCARD
import sys
import os
import time
from base64 import encode, decode
from hashlib import sha1

try:
    file=os.path.expanduser(sys.argv[1])
    jid=sys.argv[2]
    password=sys.argv[3]
    resource='vcard'
except:
    print >>sys.stderr, __doc__
    sys.exit(2)

NS_VCARD_UPDATE = 'vcard-temp:x:update'
NS_NICK = 'http://jabber.org/protocol/nick'

def hash_img(img):
    return sha1(img).hexdigest()

def base64_img(img):
    return img.encode('base64')

def get_img(file):
    try:
        os.stat(file)[6]
        fh = open(file, 'rb')
        img = fh.read()
        return img
    except Exception, e:
        print >>sys.stderr, e
        sys.exit(2)

def get_mime_type(file):
    try:
        ext = file[-4:]
        if ext == '.png':
            mime_type = 'image/png'
        elif ext == '.gif':
            mime_type = 'image/gif'
        elif ext == '.jpg' or ext == '.jpeg':
            mime_type = 'image/jpeg'
        else:
            raise ValueError, "Wrong mime-type detected. Check file suffix."
    except ValueError, e:
        print >>sys.stderr, e
        sys.exit(2)
    return mime_type

def send_vcard(conn, base64_img, mime_type, nick):
    iq_vcard = Iq(typ='set')
    vcard = iq_vcard.addChild(name='vCard', namespace=NS_VCARD)
    vcard.addChild(name='NICKNAME', payload=[nick])
    photo = vcard.addChild(name='PHOTO')
    photo.setTagData(tag='TYPE', val=mime_type)
    photo.setTagData(tag='BINVAL', val=base64_img)
    conn.send(iq_vcard)

def send_presence(conn, status, hash1, nick):
    presence = Presence(status = status, show = 'xa', priority = '-1')
    presence.setTag(name='x',namespace=NS_VCARD_UPDATE).setTag(name='photo',namespace=NS_VCARD_UPDATE).setData(hash1)
    presence.setTag(name='nick',namespace=NS_NICK).setData(nick)
    conn.send(presence)

if __name__ == '__main__':
    img = get_img(file)
    j=JID(jid)
    cl=Client(j.getDomain(),debug=[])
    conn=cl.connect()
    if not conn:
        raise Exception, 'failed to start connection'
    auth=cl.auth(j.getNode(),password,resource,sasl=1)
    if not auth:
        raise Exception, 'could not authenticate'
    send_vcard(cl, base64_img(img), get_mime_type(file), j.getNode())
    send_presence(cl, 'Updated vCard Image', hash_img(img), j.getNode())
    time.sleep(1)
    cl.disconnect()

If you need to poll the API more frequently that the API limits allow, email Alex and chances are very good that you can be accommodated. Ditto regarding something Alex referred to as a "research project" involving a data-mining feed -- presumably, this is like a customized (or perhaps random) fraction of the full public timeline firehose.

As for the full public timeline firehose via XMPP: "That would require a business discussion."

My Twitter bot works just fine for me, but Dustin is actually trying to provide a service to people other than himself, so he needs more cooperation from Twitter. Based on what Alex said, it seems that Dustin and others who are working on various bots to bring back the "track" feature via IM should be able to do so.

As for the "official" return of "track" and IM -- don't hold your breath.

I setup xmpppy on my box, thinking I could quickly set up a bot to run as one of my Google Apps for Domains users. I've spent about six or seven hours (off and on) getting this to work, though, because the documentation from Google about setting up my DNS configuration is incomplete. Thanks a lot!!! Like DNS isn't difficult enough for amateurs.

After many searches, I finally found the magic incantation, so here it is for posterity, in case that link disappears:

_xmpp-server._tcp.YOURDOMAIN.TLD. 3600 IN SRV 5 0 5269 xmpp-server.l.google.com.
_xmpp-server._tcp.YOURDOMAIN.TLD. 3600 IN SRV 20 0 5269 xmpp-server1.l.google.com.
_xmpp-server._tcp.YOURDOMAIN.TLD. 3600 IN SRV 20 0 5269 xmpp-server2.l.google.com.
_xmpp-server._tcp.YOURDOMAIN.TLD. 3600 IN SRV 20 0 5269 xmpp-server3.l.google.com.
_xmpp-server._tcp.YOURDOMAIN.TLD. 3600 IN SRV 20 0 5269 xmpp-server4.l.google.com.
_jabber._tcp.YOURDOMAIN.TLD. 3600 IN SRV 5 0 5269 xmpp-server.l.google.com.
_jabber._tcp.YOURDOMAIN.TLD. 3600 IN SRV 20 0 5269 xmpp-server1.l.google.com.
_jabber._tcp.YOURDOMAIN.TLD. 3600 IN SRV 20 0 5269 xmpp-server2.l.google.com.
_jabber._tcp.YOURDOMAIN.TLD. 3600 IN SRV 20 0 5269 xmpp-server3.l.google.com.
_jabber._tcp.YOURDOMAIN.TLD. 3600 IN SRV 20 0 5269 xmpp-server4.l.google.com.
_xmpp-client._tcp.YOURDOMAIN.TLD. 3600 IN SRV 5 0 5222 talk.l.google.com.
_xmpp-client._tcp.YOURDOMAIN.TLD. 3600 IN SRV 20 0 5222 talk1.l.google.com.
_xmpp-client._tcp.YOURDOMAIN.TLD. 3600 IN SRV 20 0 5222 talk2.l.google.com.
_xmpp-client._tcp.YOURDOMAIN.TLD. 3600 IN SRV 20 0 5222 talk3.l.google.com.
_xmpp-client._tcp.YOURDOMAIN.TLD. 3600 IN SRV 20 0 5222 talk4.l.google.com.


N.B. Those trailing periods at the end of the domain names may or may not be necessary, depending on how you update your DNS records. For example, GoDaddy inserted them for me. YMMV.