Gamefront.de appears to think so. A small news story (about a third of way page in the link) containing a single paragraph explains:
"Metal Gear on-line down load immediately possible
16.08.07 - Konami published the beta version of on-line play Metal Gear on-line one in Japan, which can be downloaded by the beta testers immediately.
This concerns a closed beta test, which runs up to 03.09.07.
CLICK PICTURE (Metal Gear on-line one, Download of the beta version)"
Without being a Japanese beta tester I am unable to confirm this, but we could be seeing some new footage or hearing some new details very soon if this is the case
NOTICE: I know this site is in German, and I apoligise for not being able to use the translated version, but that link was already used in the 'Afrika to use touch sensitive mat' story (http://www.n4g.com/ps3/News-59478.aspx)
An image of the XMB showing the beta program has appeared on the internet: