The most recent updates to Sega Direct and the Official PSOBB website have clarified the pricing situation of the game*. Although, the retail version does not go on sale until the 15th of July, the free download (reported yesterday) appears to be the final (i.e. non-Beta) version.
Similar to previous versions of PSO, a monthly fee must be paid to play the game. The retail version will include a free 30-day pass. Unfortunately, as the pages do not translate too well, it is not clear if the download version includes a similar pass.
Sega will be charging for the download version in the future, but have yet to decide as to when this will happen.
While the game might be 'free', this range of exclusive PSOBB merchandise, exclusive to Sega's Japanese e-tailing site, should help the company bring in the profits:
^This 32MB USB Pen comes with a PSOBB Neck Strap
^The 64 and 128 MB versions includes a luxury case and chain
^Mobile PC case
^Phone card
^CD case
^ Mouse Mat
Finally, the Japanese manual can be downloaded by clicking here.
*Disclaimer: Information obtained through machine translation and so may be slightly inaccurate.