Bluefalcon,
Yes, as I read it in the same way as the old rule of day of arrival and day of departure not counting applied. So if you commute in on monday and leave the same day, that day will not count, but if you arrive back on wednesday and nightstop before commuting home on thursday that midnight will count.
However I would get Balpa (I assume you are a member) to get exact clarification from HMRC. The note HMRC published on the day of the budget (quoted above) is :
http://www.hmrc.gov.uk/budget2008/master-notes.pdf
Page 239 :
Current law and proposed revisions
4. Under the current rules, when deciding if an individual is resident in the UK
for tax purposes all days spent in the UK are normally counted, except for
days on which the individual arrives in, or departs from, the UK. At the
Pre-Budget Report it was proposed that days of arrival and days of
departure should count as a day of presence in the UK, subject to an
exemption for transit passengers.
5. The changes announced today mean that on and after 6 April 2008, any
day where the individual is present in the UK at midnight will be counted
as a day of presence in the UK for residence test purposes.
6. There will be an additional exemption for passengers who are in transit
between two places outside the UK. The exemption is wider than that
proposed at the Pre-Budget Report as it caters for people who have to
change airports or terminals when transiting through the UK. It will also
allow people to switch between modes of transport, so they could fly in but
leave by ferry or train for example. Days spent in transit, which could
involve being in the UK at midnight, will not be counted as days of
presence in the UK for residence test purposes so long as during transit
the individual does not engage in activities that are to a substantial extent
unrelated to their passage through the UK. So, for example, if they take
time out to attend a business meeting then the transit exemption will not
have effect.