Are nightly builds compatible with the 5 beta?

I've got the beta running and for giggles I had it check for updates.

The update dialog tells me:
Revision 3070 (yours: 3031)
Compiled: 2010-02-11 (yours: 2010-01-30)
Notes: * (r3070) When pressing Tab key in grids and the next column does not allow editing, just focus it, instead of jumping to the next editable cell. Fixes most situations described in issue #1677.
* (r3069) Ensure we have full grid cells in source row when user clicks "Duplicate row". Fixes issue #1678.
* (r3068) Fix old row count in data grid header when rows were deleted from outside. Fixes issue #1227.
* (r3067) Prefer VT.FocusedNode over VT.GetFirstSelected in various places. Clicking a node twice deselects it and subsequent actions have an access violation. Fixes issue #1674.
* (r3066) Delphi 2010 has PNG + alpha channel support in TImageList, so we don't need PNGcomponents any longer.
* (r3065) Remove unused icons
* (r3064) Unify color depth of icons to 32 bits per pixels.
* (r3063) Surround TRIGGER creation export with custom DELIMITER, so readers (including HeidiSQL itself) are able to detect query end positions. Fixes issue #1672.
* (r3062) Remove pink foreign key icon - we already had another one. Use that consistently in both foreign key list and columns list.
* (r3061) Add pink icon for foreign key columns. Fixes issue #1669.
* (r3060) Auto create pretty foreign key name "FK_thistable_reftable" if it was not customized yet. Fixes issue #1671.


So are the nightly builds compatible with version 5.0Beta?

Not sure what the changelog has to do with your question, but: yes, sure, all recent builds are compatible to 5.0beta - whatever that means...