[osm_map lat="51.525" long="-0.134" zoom="17" type="Mapnik" width="500" height="300" marker="51.525,-0.134"]The Pearson Building, UCL Geography.
Very nice. Hopefully there will soon be an easy way to put a pin on the map using this plugin. [Update: It's been added - thanks!]
To set your own marker/pin will be feature of OSM plugin v0.8.
Thanks MiKa, I’ve picked up the new version of the plugin and have a marker in now!