Royal Mail will bring its Post & Go machines to the big international stamp show in New York, May 28 to June 4. Ian Billings noted it on his blog recently. There will be a single design showing the New York skyline from the recent Sea Travel set (how convenient). The Union Flag design will also be available, but apparently not the Machin design. I thought it worth mentioning because I believe this is the first time Post & Go stamps will be printed and sold in the US.
Sightseeing Tip: If you visit the show, be sure to see The High Line. This is a park built on an obsolete elevated rail line. The north entrance is not far from the Javits Center location of the show. The park is nearly 1.5 miles long, but even if you walk only a short distance, you will find it worthwhile.