Absolutely unconfirmed, I've just received an E-Mail from a fellow the::unwired reader that he recently tried out is recently purchased TomTom Navigator 6 maps v6.75 with his new O2 Xda diamond which runs the - yet to be announced - TomTom Navigator 7.
While TomTom Navigator 7 features minor enhancements like Map corrections, it's basically an update to the officially available TomTom Navigator 6 only. However, unlike for TomTom Navigator 6, TomTom isn't offering any purchasable maps for TomTom Navigator 7 yet but users of a German O2 Xda diamond can download one city map only - at least free of charge.

While a city map is nice, most users need maps for areas where they are - most likely - not at home and it seems the solution is already available from TomTom but not yet announced (together with the E-Mail I received the following two screenshots):

According to the E-Mail, the user just copied the - from TomTom's online shop purchased - maps of Western Europe to the inbuilt 4 GB flash memory and they instantly worked after activation.

Please take this information with a necessary grain of salt. While TomTom offers the Western Europe map at the moment for 49.95 Euro only, I haven't purchased them yet to try it out myself (maybe just to find out it's not working) but nevertheless, it was reported as working.
Maybe anyone of you have TomTom's latest TomTom Navigator maps (v6.75) and an O2 Xda diamond as well and can confirm? Anyway, until we have an official word from TomTom, there's no official support available yet for TomTom Navigator 7, which is definitely too bad!

UPDATE: Thanks for a couple of feedback E-Mails I've just received. According to these E-Mails, most users had success with purchasing the TomTom GO720 maps (Western Europe is available for 69.95 Euro) and TomTom Home 2.3. However, it's reported that Map share is also not working.

Cheers ~ Arne