These numbers and letters are meant to be descriptive. Not 'cool'.

There is no formal release cycle, and it is about hardware, so something like Ubuntu 9.04 (April 2009 A.D.) and Ubuntu 9.10 (October 2009 A.D.) doesn't work either. The OS names already follow alphabet with first letter. Bora, Chinook, Diablo, <E*_already_existed>, Fremantle, <G*_already_existed>, Harmattan. You cannot bind this 1:1 on the hardware though.

Do you already see it happening? Tons of names for products? Which have to be translated to various languages? I don't. If you manage any high number of products you are going to give them IDs which are managable. Usually, numbers. Sometimes combined with letters. That allows you for example also to categorize them further. Case in point: IPv4/IPv6, RFID, barcode.

These points also prove you're going to make an abstraction layer to make them easier to handle with in personal situation. Barcode is reference and otherwise not used. IPv4/IPv6 has DNS to make easier for humans to use. And, RFID is abstracted by metadata. (The numbers indicate a lot, and are again used as reference.)

So instead of internal name RX-51, Rover and external name N900 I suggest giving N900 also a 'codename' in addition to N900. The bad side of that is that if you go further in history, that name loses its relevance. I know Sharp Zaurus SLC1000 was Akira because I had that device, but I have no idea which device was Spitzner or Collie or Poodle while I remember and know characteristics of SL5500, SL6000, SLC7?0, SL8?0, SL1000, SLC3000, SLC3100, SLC3200. The same confusing situation arises with 'The iPhone' which always refers to the latest iPhone, or so it seems. Past discussion, including wiki pages, quickly gets confusing or bitrotten after a new iPhone comes out while the actual product names are actually informative.