I'm not sure where you got this impression. Take a look at
Indigo the communications pillar in Longhorn. this allows developer to easily communicate reliably and securely. From the FAQ:
"Indigo includes support for the latest Web services standards, including SOAP. Applications built with Indigo will interoperate with any application built on infrastructure that also conforms to these standards. This includes IBM WebSphere, BEA WebLogic
and other Web services built in J2EE that are SOAP-standards compliant. Microsoft is deeply committed to platform interoperability, and an active member of the key standards organizations defining the latest standards for Web services including SOAP and XML."
In the uk microsoft wrote a website for the UK goverment allwoing for more communication between departments and the general public it was meant to be a step towards e-democracy, big thing in the UK press, microsoft was awarded the contract, they kept going
on and on about how they will use open standards , all machines would be able to use it, they ended up using some XML technology. When the system was built, it did not work on all machines only microsoft ones, it used open standards then changed them to ensure
that other machines could not use it. It cost the UK goverment lots of money.
TCP/IP another open standart windows uses, does not follow this standard again it has been changed, leading to the set up of samba, to allow networking between windows and the rest of the world.
There is a choice of browsers and os's currently using https, but this has mainly been brought around by the increasing use of apchae and linux as web servers, over 50 % last time i checked. Longhorn may be a last ditch attempt to retake it by locking people
into techs like xaml.
With all these issues only time will tell