Apple's MobileMe service will be going live on July 9, 2008 sometime between 6 p.m and 12 a.m PT per the current .Mac Web site, which reads:
"As part of the MobileMe launch, www.mac.com will be taken offline at 6pm PT on Wednesday, July 9th. Members will be unable to access www.mac.com or any .Mac services during this time with the exception of .Mac Mail accessed via a desktop application, iPhone, or iPod touch."
MobileMe will be available as soon as possible during this maintenance window.
The shift will come in time for the iPhone 3G launch on July 11. More information about MobileMe, the replacement for Apple's .Mac service, can be found here.
Current .Mac subscribers are reporting the ability to send and receive emails at their new @me.com addresses.
MobileMe retails for $99/year, but iPhone 3G (or Mac) buyers will be able to pick up a year's subscription for $69 on July 11th.
If you are lucky enough to find a discounted copy of .Mac, from Amazon for example, it can be activated now and upgraded automatically to to MobileMe when the service becomes available.