Maximum PDF size updated???

Sorry, I made a conversion error, the maximum page size is 381 km (15 million inches).

This is from the PDF Reference 1.7:

177. In PDF versions earlier than PDF 1.6, the size of the default user space unit is fixed at 172 inch.

In Acrobat viewers earlier than version 4.0, the minimum allowed page size is 72 by 72 units in default user space (1 by 1 inch); the maximum is 3240 by 3240 units (45 by 45 inches).

In Acrobat versions 5.0 and later, the minimum allowed page size is 3 by 3 units (approximately 0.04 by 0.04 inch); the maximum is 14,400 by 14,400 units (200 by 200 inches).
Beginning with PDF 1.6, the size of the default user space unit may be set with the UserUnit entry of the page dictionary. Acrobat 7.0 supports a maximum UserUnit value of 75,000, which gives a maximum page dimension of 15,000,000 inches (14,400 * 75,000 * 172). The minimum UserUnit value is 1.0 (the default).

200 x 200 inches is Distiller’s limit for PostScript. It’s based on the Windows printer driver limitation.

Yes, the software limit is usually 200x200 inches (502x502 cm), which corresponds to the print format limit of older versions of Windows.

According to the PDF format specifications the maximum size for a PDF file is 32000x32000 kilometers.

No, the limit has not been updated. But it is a software limit, not a format limit, so different apps may set different limits. But when you try to get it back into Acrobat it will fail and may display as blank, print incompletely or not at all etc.