I had a quick look around and there are SetLocation and GetLocation functions using XEP-0080 in Telepathy-gabble itself. What I could not check however is whether this interface is available in the version on the N900 as I don't have one right now and didn't really feel like digging into code.

I sad This microblogging service (via xmpp only) support XEP-0080 - juick.com

I wouldn't get too disappointed just yet.
For all I know one should be able to get the location from the GPS from within custom software and assuming the telepathy dbus call is available on the N900 sending a XEP-0080 PEP event should be pretty straight forward. (As in < 30 lines of code for a basic non-configurable implementation)

<30 lines and still no go?

I think what Florob meant was a <30 lines implementation for technically sending/receiving location via XEP-0080.

That's no use at all ATM. Sending yes (given the other party uses Empathy with Geoclue enabled), but receiving stll needs some UI to actually display the user's location - which is more work.

People will not feel the need to code this as long as major desktop clients don't support in out of the box so they see what it does... and how it could do the same on the N900.

My hope is that this will happen once Ubuntu adds Geoclue support, which I think is scheduled for Lucid Lynx.
The only sad thing is that Ubuntu will lead they way and N900 will follow... I'd rather have it the other way round.

I am currently working on web interface, which allows to display XEP-0080. The sending of the XEP-0080 definitely helps me with development of this web page.

Its currently at http://pcpanel-l205.fit.vutbr.cz/jabinfo/

EDIT: I see that the Azimuth and Mapbuddy application works well.