A 'monger' is literally someone who 'sells' something (literally or figuratively) - as in a 'fishmonger' or 'ironmonger'. 'Mongering', then, is the practice of 'selling' something - in this context it is 'selling' in the way that a newspaper can be said to be selling a story (rather than for money!).
As for Dell - I know for certain that Fujitsu-Siemens will be offering the 2003 upgrade, inges-PDA has confirmed that HP will be offering it, in a couple of places people have stated that Toshiba reps have said they will offer it... I'm sure Dell will compete with all of them for both providing the U/G and the time-frame in which they offer it.
Remember - so far all of us with knowledge of upgrades from various manufacturers are reporting info from reps or leaks - no-one will be announcing anything officially before 23 June (trust me - MS have made it clear that this is not to happen!). Dell have obviously just not 'leaked' yet!
As Ed says - no matter how good the source of leaked info - until MS/FSC/HP/Dell/Toshiba officially confirm it, it remains in the realm of rumour...