can't open files larger than 2gb

Can you confirm this is on a 32-bit system only (the 2GB file limit only applies to 32-bit systems). If so the bug is, perhaps, that 32-bit Vim doesn't complain when asked to open a file over 2GB.

The example given in the bug report was from a 32bit system (hyperthreaded P4).

Confirming.
Based upon Andrew's comments: it appears that vim doesn't report the limitation to the user & then proceeds as though the large file doesn't exist.

Upstream patch 7.2.413 adds largefile support. Some of the Vim packages (those which support scripting via Perl) already have this transitively via libperl's CFLAGS. I'll be uploading a new Vim package to Debian with patch 7.2.413 soon.

This bug was fixed in the package vim - 2:7.3.035+hg~8fdc12103333-1ubuntu1

---------------
vim (2:7.3.035+hg~8fdc12103333-1ubuntu1) natty; urgency=low

  * Merge with Debian unstable (lp: #662276):
    - Use case-insensitive matching for month and day of week names in
      crontab's syntax file (lp: #517019 aka Debian bug #568378).
    - Fix sqlcomplete's <Left>/<Right> maps so they don't interfere with
      normal usage (lp: #584797 aka Debian bug #560083).
    - [7.2.386] KDE 3.1 focus hack causes problems for other window managers
      (lp: #535341).
  * Remaining changes:
    - debian/control:
      + Drop vim-lesstif package and lesstif2-dev build-dependency.
      + Rename Vcs-* to XS-Debian-Vcs-*.
    - debian/rules:
      + Don't build the vim-lesstif variant in Ubuntu.
    - debian/runtime/debian.vim.in:
      + Add Launchpad integration to the Help menu if launchpad-integration is
        installed.
    - debian/runtime/vimrc:
      + "syntax on" is a sane default for non-tiny vim
    - debian/patches/debian/ubuntu-grub-syntax.patch:
      + Add Ubuntu-specific "quiet" keyword.

vim (2:7.3.035+hg~8fdc12103333-1) unstable; urgency=low

  * Pull patches 001 - 035.
    + More robust YAML highlighting. (Closes: #535682)
  * debian/rules:
    + Stop overriding CFLAGS on the command-line when invoking make. Upstream
      enforces an upper-limit of 1 for _FORTIFY_SOURCE due to the use of
      flexible arrays in nested structs, which improperly cause Vim to crash
      with _FORTIFY_SOURCE=2.
    + Use DEB_HOST_ARCH_OS instead of DEB_HOST_GNU_SYSTEM to determine whether
      Linux-specific functionality is enabled.
    + Use dpkg-vendor to change build configuration when building on Ubuntu.
      Thanks to Michael Bienia for the patch.
  * Make helpztags capable of generating tags files for non-English help
    files. (Closes: #600248)
  * Debian runtime:
    + Add natty as a recognized distribution. (Closes: #600560)
    + Add metapackages as a recognized section. (Closes: #600562)
    + Remove etch as a recognized distribution.
  * debian/control: Add dpkg-dev (>= 1.15.1) Build-Depends for dpkg-vendor.

vim (2:7.3.000+hg~ee53a39d5896-1) unstable; urgency=low

  * New upstream release.
  * debian/rules:
    + Explicitly use the dynamic loading Python interfaces.
    + Remove cleanup from clean target which are now properly handled by
      upstream's Makefile.
  * Update version information in documentation.

vim (2:7.3f.20100812+hg~20e83abf88b1-1) experimental; urgency=low

  * Merge latest 7.3f pre-release.
    + Correctly restore multi-byte terminal titles when exiting Vim. (Closes:
      #558153)
    + Highlight text inside math zones correctly for tex files. (Closes:
      #509908)
    + Recognize nested cite regions in tex files. (Closes: #444288)
    + Support syntax highlighting of bash's $"". (Closes: #473736)
  * Patches merged upstream:
    + perl-indent-block.patch
    + logcheck-ftplugin.patch
    + tex-syntax-verbatim-spell.patch
  * Enable Lua scripting.
    + Add liblua5.1-0-dev and lua5.1 to Build-Depends.
    + Enable lua interface via dynamic loading.
  * Switch Perl interface to dynamic loading.
  * debi...